Air University Review, January-February 1983

Linebacker and the Law of War

W. Hays Parks

On Good Friday, 30 March 1972, three North Vietnamese divisions crossed the demilitarized zone (DMZ) separating the Democratic Republic of Vietnam from the Republic of Vietnam and invaded the northernmost provinces of the latter. Before the Easter weekend was over, twelve of Hanoi’s thirteen regular combat divisions were carrying out military operations in South Vietnam. The 120,000-soldier force was equipped with more than 200 T-34, T-54, and PT-76 tanks as well as mobile radar-controlled antiaircraft weapons and portable surface-to-air missiles. The North Vietnamese invasion, timed to exploit the adverse weather during the transition from the northeast to southwest monsoon and initiated to enable Hanoi to strengthen its political hand in the Paris peace talks, prompted the second major bombing campaign over North Vietnam by the United States. Named Linebacker I and II, these operations would have a major effect on thwarting North Vietnamese politico-military efforts before they were concluded nine months later.

The preceding campaign, Rolling Thunder, had been terminated north of 19° N almost exactly four years earlier, with a total cessation of offensive air operations over North Vietnam occurring seven months later. Discussions seeking a diplomatic solution to the Vietnam War had commenced in March 1968. Undoubtedly in recognition of its effect, North Vietnamese officials argued that serious discussions could not take place until U.S. bombing of the North had ceased. The Johnson administration agreed to stop the bombing on 31 October 1968, with a tacit agreement that

• North Vietnam would not use the area in or near the DMZ to attack U.S. forces or otherwise take advantage of U.S. restraint;

• Vietcong forces would not strike major cities in South Vietnam; and

• The United States could continue reconnaissance flights over the DMZ and those areas of North Vietnam immediately adjacent to the DMZ to verify North Vietnamese compliance with the first condition of the agreement.1

In the years following the conclusion of Rolling Thunder, United States air power continued to support military operations in South Vietnam. North Vietnamese direction and support of the war in South Vietnam did not cease but shifted resupply and reinforcement emphasis to the Ho Chi Minh Trail, winding its way through Laos and Cambodia. The United States responded, concentrating its air power on interdiction of the trails while permitting North Vietnam the sanctuary of its supply base in the north. As North Vietnam rebuilt itself, President Richard M. Nixon announced his program for Vietnamization of the war and withdrawal of U.S. forces. From an authorized high of 545,000 in 1969, U.S. personnel in South Vietnam were to be drawn down to 69,000 by 1 May 1972, but with a promise by President Nixon to the North Vietnamese leadership that he would react strongly to any overt North Vietnamese offensive.

The cessation of bombing over North Vietnam had not brought peace but a diplomatic stalemate as North Vietnam reconstructed its defenses and supply routes. Using the peace talks as a platform for propagandistic harangues, the North Vietnamese eschewed diplomatic resolution of the conflict, instead buying time until the Easter offensive, when they had "brutally and cynically chosen a test of arms."2

The U.S. response to the North Vietnamese invasion was immediate. B-52 Arc Light missions in South Vietnam against infiltration routes and staging areas increased, and B-52 forces in the theater increased dramatically with the Bullet Shot deployment of B-52Gs to Guam. Over the next weeks Marine squadrons deployed to Da Nang, Bien Hoa, and the "Rose Garden" at Nam Phong, Thailand; Navy carrier support doubled; and Air Force tactical air (TACAIR) units rejoined the war from Korea and the United States. The first priority of returning air units was to support South Vietnamese forces directly so that the ground battle in South Vietnam could be stabilized; the second was to turn air power efforts north.

Unlike the gradualism of Rolling Thunder, there was little hesitation in l972.3 On 2 April 1972, the national command authorities (NCA) through the Joint Chiefs of Staff (JCS) authorized air strikes against military targets and logistic supply points north of the DMZ to 17° 25’; this was increased to 18°N on 4 April and to 19° N on 6 April. On 9 April, 15 B-52Ds struck Vinh railroad yard and Vinh POL (petroleum, oil and lubricants) supply. It was the first use of B-52s in North Vietnam since 28 October 1968. Three days later, 18 B-52s struck Bai Thuong airfield. On the weekend of 15-16 April, B-52s and Navy and Air Force TACAIR struck military storage areas and POL targets in the areas surrounding Hanoi and Haiphong. One week later, similar targets were attacked at Hamm Rong and Thanh Hoa.

As with most military operations, these attacks served multiple and interrelated military and political purposes. They disrupted the flow of war supplies supporting the North Vietnamese invasion of South Vietnam; warned Hanoi that if it persisted in its heavy fighting in South Vietnam, it would face mounting raids in the north; demonstrated continuing U.S. support for the government of South Vietnam which, as in Rolling Thunder, would bolster its will to defend itself. Furthermore, these attacks were intended to persuade Moscow to use its influence to encourage a political rather than a purely military resolution of the conflict.

U.S. military responses were coupled with diplomatic efforts to forestall further fighting. National Security Adviser Henry Kissinger traveled to Moscow on 20 April for secret talks with the Soviets to enlist their assistance in facilitating a return to the peace talks and to Paris to meet secretly with North Vietnamese negotiator Le Duc Tho on 2 May. Kissinger’s appeals were spurned out of hand by the latter, whom Kissinger describes as bewildered by the quick response of U.S. air power to the North Vietnamese invasion. Similar efforts by U.S. Ambassador William J. Porter to resume the Paris peace negotiations on 27 April and 4 May were met by North Vietnamese demands for U.S. and South Vietnamese surrender.

As a result of North Vietnam’s intransigence, President Nixon addressed the nation on 8 May to announce that the North Vietnamese ports of Haiphong, Cam Pha, Hon Gai, and Thanh Hoa, as well as smaller inlets harboring North Vietnamese patrol boats, were to be closed through naval mining. The mines were to be laid at 0900 on 9 May (Saigon time), to activate at 1800 on 11 May, thus affording third-country shipping the opportunity to depart the mined harbors unharmed. Simultaneously, he announced air operations throughout North Vietnam. These air operations (Linebacker I) would continue until the formal cessation of hostilities in January 1973; a separate operation, Linebacker II, would take place concurrently from 18 to 29 December l972.4

Linebacker I was more ambitious in purpose than Rolling Thunder. Its objectives were to curtail the military resupply of North Vietnam from external sources; to destroy internal stockpiles of military supplies and equipment, wherever located; to destroy targets throughout North Vietnam which were providing direct support to the nation’s war effort in South Vietnam; and to restrict the flow of forces and supplies to the battlefield, thereby inhibiting Hanoi’s new-found dependency on advanced means of warfare. The overall objective was to sap the foundations of the enemy’s desire to prolong the conflict by hampering its ability to conduct sustained combat operations, to induce its return to meaningful negotiations for a diplomatic settlement of the conflict. The Nixon administration shared the view of its predecessor that U.S. national objectives in the Vietnam War were limited. Like Rolling Thunder, neither Linebacker I nor II was intended to destroy the Hanoi regime, compel the North Vietnamese people to adopt another form of government, or devastate North Vietnam. If thoughts of ground invasion were remote during Rolling Thunder, they were nonexistent during Linebacker I and II; President Nixon had directed at the outset of Linebacker I that stand-down of U.S. ground forces would continue.5 The last U.S. ground combat unit was withdrawn three months later, on schedule. From the beginning, U.S. efforts were dependent exclusively on air and naval power.

In order to seal off North Vietnam from external supply, Navy A-6 aircraft closed North Vietnamese ports by aerial mining in an operation named Pocket Money. In doing so, Pocket Money forces were permitted for the first time to implement JCS recommendations made in 1964 in the planning of Rolling Thunder, but essentially avoided during the former campaign. As one Air Force officer noted of Rolling Thunder, "instead of destroying the war-supporting pillow at the port, efforts were expended chasing the feathers all over Southeast Asia." Hanoi received 85 percent of its goods, on 2.1 million tons, through the port of Haiphong during 1971, including all of its POL; the failure to close the ports of entry was viewed by the planners of Linebacker and by the Nixon administration as one of the principal weaknesses of Rolling Thunder. Linebacker I forces then cut the northwest rail line running between Hanoi and Kwangsi Province in China; cut the northeast rail line between Hanoi and Yunnan; and interdicted the eight major highways from China and the water-borne logistics craft (WBLC) on the waterways of North Vietnam.

Rolling Thunder forces had been impeded further in the successful prosecution of campaign objectives by NCA-imposed geographic restrictions that severely curtailed air strikes in areas north of 20° N, providing North Vietnam with a sanctuary for its greatest military-industrial area for much of that campaign. They were impeded further by denial of authorization to attack legitimate targets because of a fear by the NCA of unacceptable losses by U.S. forces and of targets in heavily populated areas because of a paranoiac fixation with regard to any incidental civilian casualties (based in part on apparent ignorance of belligerent rights under the law of war). Rolling Thunder also suffered from stringent strike restrictions that placed U.S. forces at undue risk and from frequent bombing halts which President Johnson subsequently acknowledged had a net result of "zero . . . indeed . . . less than zero."6

The North Vietnamese undoubtedly interpreted the Johnson conduct of Rolling Thunder as a manifestation of a lack of determination, as well as identifying a vulnerability of the U.S. government to sustained propaganda alleging violations of the law of war. Repeated disinformation, however false, resulted in increased restrictions on U.S. strike forces and target denial. After rebuilding its defenses around Hanoi and Haiphong, the Hanoi government was willing to engage in some risk taking with regard to any new aerial campaign over North Vietnam, convinced that it could win any test of national will with the United States.

President Nixon, profiting from the errors to his predecessor, recognized the challenge facing him. In a memorandum supporting bombing of the North, he noted:

[North Vietnam] has gone over the brink and so have we. We have the power to destroy his war-making capacity. The only question is whether we have the will to use that power. What distinguishes me from Johnson is that I have the will in spades.7

In studying the lessons of Rolling Thunder, President Nixon was bothered by the "dreary ‘milk-runs’ which characterized the Johnson administration’s bombing in the 1965-1968 period."8 On 6 April, President Nixon and Kissinger met with General John W. Vogt, whom President Nixon had just selected to command Seventh Air Force. After brief discussion of U.S. objectives in the new air campaign, President Nixon asked General Vogt what support he required to accomplish his mission. General Vogt’s requests were few, but one in particular would have significant impact on the success of Linebacker I. General Vogts asked President Nixon not to repeat the Johnson administration practice of exclusive NCA control of target selection. President Nixon assented without hesitation.9

The White House return of special trust and confidence to the military commanders responsible for execution of national policy was important for a number of reasons. During Rolling Thunder, targets had been "dribbled out" by the White House in no rational sequence. There was no restrike authority, or restrike authority was severely limited. Numerous targets were placed off limits for the duration of Rolling Thunder, or a substantial portion thereof. In Linebacker I, most of the list of targets10 became the validated target list,11 enabling the operational commands to identify target systems, establish target priorities, and attack them in a logical sequence. Field commanders possessed restrike authority. The list was supplemented as new targets were identified.

In Rolling Thunder, the White House selected targets weekly—subsequently at less frequent intervals—without consideration for the weather over North Vietnam. Only validated targets could be attacked during the prescribed time frame, and most targets remained validated only during the time frame prescribed. If weather prevented attack of a validated target, the target generally was not revalidated immediately; often it would disappear from the target list for months.

Linebacker I forces were not so constrained, permitting greater flexibility in planning and more effective utilization of forces. Targets were attacked by system. Thus Linebacker I forces were able to attack all power sources in a very short time (with the exception of the Hanoi thermal power plant, which remained off limits until Linebacker II). In contrast, during Rolling Thunder, the White House would authorize the attack of power plant "A," withhold authorization for attack of power plant "B" for two months, then authorize air strikes against power plant "C" three months later, by which time power plant "A" had been restored to operation because of a lack of restrike authority to inhibit its recovery. Such a drawnout process enabled the North Vietnamese to develop a cushion in each target system to mitigate the effect of U.S. air strikes. In the case of the power system, the North Vietnamese had enough time to import 2000 portable generators to offset the effect of airstrikes against its power plants.

Similarly, if Linebacker I forces were unable to attack portions of a target system in one part of North Vietnam because of adverse weather, they would concentrate on those portions of the target system that were weather clear. This operational flexibility enabled Linebacker I planners to "play" the enemy defenses. During Rolling Thunder, repetitious strikes on the targets validated for the week enabled North Vietnam to concentrate its forces to defend the target, once identified. By contrast, Linebacker I forces could attack targets in one area until the enemy adjusted its defenses, then shift its efforts to a less-defended set of targets.

Some political restrictions remained, although they were reduced substantially when compared with those of Rolling Thunder. A buffer zone extended south from the Chinese border for 30 miles from the Laos-North Vietnam border to 106°E longitude and 25 miles from l06°E east to the Gulf of Tonkin. The buffer zone was intended to prevent entry by U.S. aircraft into Chinese airspace; it did not permit the North Vietnamese a no-strike sanctuary for the staging and storage of military supplies, as occurred during most of Rolling Thunder. Strikes at targets in the buffer zone were authorized if operational commanders deemed them necessary. For example, while interdicting the northeast rail line, six spans of the Lang Giai rail bridge were downed on 25 May, and the rail switching yard and road bridge at Lang Son were attacked on 6 June. Each lay within the buffer zone.

In Rolling Thunder, restricted areas of 30 and 10 nautical miles (nm) were established around Hanoi and Haiphong, respectively. Targets within those areas could not be attacked without specific NCA approval. Prohibited areas of 10 and 4 miles were placed within the restricted areas. Attack of targets within those areas also required NCA authorization which was less likely than for targets within the restricted areas. In Linebacker I, the prohibited areas ceased to exist, and the restricted area decreased to 10 and 5 nm, respectively. Attack of some lawful targets continued to be prohibited for political reasons: Hanoi-Gia Lam airfield, used concurrently for military and civilian purposes; the aforementioned Hanoi thermal power plant, located in a heavily populated area; the Hanoi international radio communication system; Lao Dong Party headquarters, from which the war was directed;12 the Ministry of Defense Army and Area Capital Headquarters, a 150-acre complex located in a heavily populated area of Hanoi; economic targets not directly associated with the military effort; and the Haiphong docks.

In contrast to Rolling Thunder, where the White House selected all fixed targets, Linebacker I operational commanders selected targets for attack from the validated target list, subject only to the guidance that the JCS be informed of target selections 24 hours prior to their strike, and that B-52 strikes north of Route Package I would be approved by the Secretary of Defense.13 Strikes in the Hanoi/ Haiphong area were prohibited during President Nixon’s visit to the Soviet Union from 21 May to 5 June and during the visit of Soviet President Nikolai V. Podgorny to Hanoi in mid-June.

Not all stand-downs were the result of the diplomatic efforts under way concurrent with Linebacker. In early September, the JCS sought authority for attack of most of the railroad bridges within the buffer zone in a special operation code-named Prime Choke. On 3 September, all bombing north of 20°N was suspended for 24 hours to prepare the aircraft and crews for a highly coordinated maximum effort. Under strict command supervision, Prime Choke was undertaken successfully from 4 to 16 September by selected Air Force F-4 units using laser guided bombs (LGBs). Prime Choke targets were restruck truck between 26 September and 19 October.

Targeting guidance was relaxed and for the first time reflected accurate application of the law of war. In contrast to Rolling Thunder restrictions, which maintained the impractical political restriction of avoiding any injury to the civilian population, the JCS instructed operational commanders to exercise reasonable precautions to avoid incidental damage to prisoner-of-war camps, shrines, hospitals, and third-country shipping, and to minimize incidental or collateral civilian casualties and damage to civilian property consistent with strike force security. A clear distinction was made between the prohibition on attack of the civilian population per se, which is prohibited by the law of war, and incidental injury to civilians working in lawful targets or those injured or killed while taking part in the hostilities, such as manning antiaircraft defenses.14 Fixed targets in proximity to water control facilities such as irrigation dams or dikes required special justification for validation by the nominating authority. Strike forces could respond in self-defense to antiaircraft artillery fire from third-country shipping.

Besides improved political support for the task assigned, operational command abilities had increased substantially through the greater force capability of the A-7 and F-111; enhanced electronic countermeasures such as the Marine EA-6A and Navy EA-6B; improved tactics, targeting, and weaponeering; and through use of precision guided munitions (PGM). The electrooptically guided bomb (EOGB) and laser guided bomb were to have a pronounced effect on the success of Linebacker I operations. One of the better examples of their effectiveness was the downing of the Thanh Hoa bridge. The Navy and Air Force flew hundreds of sorties against the bridge in the course of Rolling Thunder without success; the bridge was downed on 13 May 1972 by 14 Air Force F-4s using Mk-84 and M-1l3 LGBs.15 Similarly, on 10 June 1972, F-4s struck the Lang Chi hydroelectric facility, 63 miles up the Red River Valley from Hanoi. The Soviet-built, 122,500-watt installation was capable of supplying 75 percent of the electricity for Hanoi’s industrial and defense needs, and its operation threatened to offset Linebacker I accomplishments in the attack on the North Vietnamese power system. It was a vital target. However, it had been estimated that as many as 23,000 civilians would perish if the dam were breached, a cost the NCA deemed impermissible. With the experience of earlier missions, Seventh Air Force was confident it could neutralize the hydroelectric facility without breach of the dam. The mission was authorized, with the absolute condition that damage to the dam was forbidden. The strike force placed 12 Mk-84 LGBs through the 50 x 100-foot roof of the main building at the base of the dam, destroying its turbines and generators and shutting the power plant down for the duration of Linebacker I, without damage to the dam or spillway.

The increased authority allowed operational commanders was met by acceptance of the concomitant responsibility. Targeting personnel evaluated targets to be nominated for attack with a view to target location and the threat to the civilian population. All reasonable precautions were taken to minimize collateral civilian casualties through tactics and selection of means and methods to suit the target. For example, Seventh Air Force directed that targets in heavily populated areas were to be attacked with LGBs only. Bomb damage assessment (BDA) coverage was made of each strike to assess mission success but also to ensure adherence to mission parameters, including the rules of engagement. This command supervision paid off on several occasions, as it provided the United States with the ability to rebut the North Vietnamese disinformation campaign against U.S. air operations. As a result of the combination of improved weapons, tactics, and rules of engagement, Linebacker I in three months had greater impact on the ability of North Vietnam to wage war than Rolling Thunder had in three and a half years, and the North Vietnamese invasion of South Vietnam rapidly lost momentum. In late June, North Vietnam signaled its willingness to return to the peace table. Profiting from his predecessor’s experience, President Nixon elected to maintain the military pressure on North Vietnam through the summer and fall of 1972. The bombing of targets throughout North Vietnam would continue as a means to induce North Vietnam to abandon its plan of conquering South Vietnam through military force and to choose a diplomatic settlement of the conflict.

Because Linebacker I operations were planned and executed with a conscious consideration of the law of war, the North Vietnamese were was unsuccessful in manipulating international public opinion against the bombing through allegations of indiscriminate bombing. Their one major disinformation effort related to the alleged bombing of the earthwork dikes of the Red River Valley and failed abysmally.

The terrain of the Red River Valley running from the northwest to southeast in the northern sector of North Vietnam has been described as a giant drainboard as the water from the monsoon seasons rushes to the Gulf of Tonkin. To meet the floodwater, which usually crests between July and September, the North Vietnamese over the centuries have constructed a complex system of almost 2500 miles of earthen dikes, dams, and sluice gates. Other dikes prevent seepage of sea water into crop-growing areas, while many primary dikes are backed up by a second line of dikes. The system was expanded by 50 percent between 1953 and l972, with many previous dikes growing in width and height. The increase vastly complicated maintenance, already a constant preoccupation of the North Vietnamese government and people. In 1971, the Red River Valley suffered its worst flooding in three decades. One 30-mile section of the dike system was breached. The force of water unleashed through this and other breaches on the primary dikes caused wide- spread erosion, cut long stretches of irrigation canals, and washed out many pumping stations; prolonged inundation undermined both the primary and secondary dike systems. More than one million acres of riceland were flooded and the crops destroyed, forcing North Vietnam to import food from the Soviet Union and China.16 Because much of the effort of the civilian population normally dedicated to dike maintenance had been diverted to support the war effort, the government of North Vietnam faced the 1972 flood season with ill-maintained dikes and the possibility of residual stress from the 1971 floods. Partly in the attempt to rally international public opinion against Linebacker I but primarily to increase the efforts of its people to maintain the dikes and to absolve itself of responsibility for failure to repair the system since the 1971 floods, the North Vietnamese commenced a major propaganda campaign in June 1972 alleging intentional attack of the dikes by U.S. forces.

Dikes and dams can be legitimate targets from either a military or law of war standpoint, provided their destruction leads to a specific military advantage. The Möhne and Eder dams were breached by Royal Air Force Lancaster bombers of 617 Squadron on 17 May 1943 in an effort to impede military-industrial manufacturing in the Ruhr Valley,17 while RAF and U.S. Army Air Forces (USAAF) bombers breached key points in the Dortmund-Ems and Mittelland canals as part of the attack on the German lines of communication in late l944.18 In the Korean War, breach of the Toksan and Chasan irrigation dams in May 1953 rendered unserviceable the two main railway lines and parallel highways into the North Korean military, industrial, and political center of Pyongyang.19

Attack of the North Vietnam dike system never was seriously contemplated during U.S. air operations over the nation. In a memorandum dated 18 January 1966, Assistant Secretary of Defense for International Security Affairs John T. McNaughton proposed destruction of he Red River Valley dams and dikes to shallow-flood the rice fields, thereby leading to "widespread starvation" of the civilian population of North Vietnam, which the United States could offer to rectify "at the conference table."2° Seccretary of Defense Robert S. McNamara rejected McNaughton’s suggestion.

There were legitimate reasons for attacking the dike system. The country’s major transportation waterways the Red River, the Thai Binh River, and the connecting Canal des Rapides and Canal des Bambons—were vital lines of communication between the major urban centers of Hanoi and Haiphong and lesser cities. Raw materials, such as coal from the Cam Pha and Mao Khe mines for use in the nation’s myriad thermal power plants, were moved by the waterways. As the northwest and northeast rail lines from China were cut, military use of the waterways increased. Breach of the dikes would have been one way to attack this vital line of communications; this was the rationale behind the 1944 attacks on the Dortmund-Ems and Mittelland canals and would not have been prohibited by the law of war. United States forces operating over North Vietnam sought, and found, an alternative means for impeding WBLC rather than breach of the dikes: the use of air-delivered bottom-laid mines and armed reconnaissance against WBLC. This program, begun in March 1967 and renewed during Linebacker I, was effective for military and law of war reasons. Sunk WBLC blocked waterways and required more effort to salvage than necessary to repair breaks in the dikes while minimizing the likelihood of collateral injury to the civilian population.

U.S. investigation of North Vietnamese allegations revealed that there was some slight damage to some dikes but that their bombing was unintentional, their damage minor, and that no major dike had been breached. None of the damage was in the Hanoi area or involved the primary dike system protecting Hanoi. Nearly all damage was downstream from Hanoi as well as downstream from the major breaks resulting from the 1971 floods. All dike damage occurred within the proximity of specific targets of military value, such as POL storage facilities or road or rail lines of communication. For example, the rail and POL lines between Hanoi and Haiphong were attacked on 14 June at Hai Duong, a city on the Song Thuong midway between Hanoi and Haiphong. There was some slight collateral damage to dikes in proximity to the targets, which Hanoi alleged was intentional.

The law of war recognizes the inevitability of incidental damage in the attack of legitimate targets. What is prohibited is the intentional attack of civilian objects the destruction of which will have no value, the use of means of methods of warfare incapable of distinguishing between military targets and civilian objects, or incidental damage so extensive as to be tantamount to the intentional attack of civilian objects or the civilian population per se. Review of bomb damage assessment photographs at the points alleged by the North Vietnamese as well as detailed photographic coverage of all parts of the Red River Valley confirmed the unintentional, random nature of the damage, resulting from the attack of legitimate targets.21

The dike issue was complicated by North Vietnamese use of the dikes for military purposes. A large number of dikes served as part of the road network for North Vietnam, which were used to transport military equipment and personnel south to support the offensive in South Vietnam. Because President Johnson declared during Rolling Thunder that the

United States would not attack the dikes, the North Vietnamese exploited the situation by placing AAA gun positions, ground-controlled intercept (GCI) radar, and surface-to-air missile (SAM) sites atop or adjacent to dikes, and storing POL alongside or on top of dikes as a shield against attack. All were legitimate targets. The air defenses not only threatened U.S. forces but, in inhibiting bombing accuracy in the attack of lawful targets, were likely to lead to greater incidental civilian casualties. Nonetheless, the Johnson administration denied repeated requests for authorization to attack the air defense sites. When they were finally authorized for attack during Linebacker I, it was with the stipulation that the targets were to be attacked with weapons that would minimize the risk of structural damage to the dikes. This was accomplished through the use of napalm, strafing, cluster munitions, and other antipersonnel weapons.22

The North Vietnamese continued their dike-bombing propaganda campaign through the dog days of August 1972. Despite the traditional late-summer paucity of news, their efforts received little serious attention and little more than the usual support of a movie star and individuals such as out-of-office political gadabouts.23 Even leading antiwar activists doubted its validity,24 undoubtedly because the Nixon administration met the issue squarely and produced evidence to rebut the North Vietnamese allegations. North Vietnamese credibility on the issue was damaged by a government admission published in the newspaper Hanoi Mo early in their propaganda campaign acknowledging that repair of portions of the dikes damaged by the 1971 floods had not yet met "technical requirements." Once the 1972 season passed without significant flooding, the dike-bombing issue subsided, notwithstanding continuation of Linebacker I.

The monsoon season that threatened the Red River Valley dike system also jeopardized the effective continuation of Linebacker I operations over the same area, which included the strategically important Hanoi/Haiphong military-industrial complex. Recognizing the degree to which weather inhibited TACAIR operations,25 targeteers in early August began a detailed review of the target list to ascertain those targets against which all-weather bombing techniques by B-52s and TACAIR could be utilized. Navy aircraft on combat air patrols also began providing data for prediction of weather windows for LGB employment. Major criteria for B-52 employment were that a nominated target be readily identifiable for radar targeting purposes or be sufficient in size to be attacked by a three-ship B-52 cell with minimal likelihood that the bomb train would fall outside side the target. Targets fitting those criteria were airfields, railroad yards, large-area military warehouse and storage areas, and some power plants, petroleum products storage areas SAM sites, and SAM storage areas.26 Once targets meeting these criteria were identified, targeteers worked with photo interpreters to build radar montages of the targets to facilitate target identification, selected an axis of attack for each target (minimizing overflight of built-up areas immediately prior to and after crossing the bomb release line), and took other steps to maximize the capabilities of available assets while minimizing the risk to the civilian population.

On 1 September, CINCPAC established a joint targeting committee to review TACAIR targets nominated by PACAF and CINCPACFLT for validation by the JCS. The committee stressed target location vis-à-vis the threat to populated areas, location of U.S. and allied prisoners of war, and attack of the air defense system (including AAA and SAM installations, airfields, and command, control, and communication facilities associated with the air defense system), neutralization of which would optimize freedom of action and safety for U.S. strike and reconnaissance forces—thereby enhancing the ability of strike forces to put bombs on target while decreasing the likehood of incidental civilian casualties. Concurrently CINCSAC and CINCPAC began a detailed review of targeting plans for the coordination and sustained use of B-52s against targets in the northeast sector of North Vietnam. The purpose of B-52 use was threefold:

• to provide maximum destruction of the North Vietnamese air defense system to lower U.S. aircraft risk and attrition, reduce mission support requirements, and provide U.S. strike forces greater freedom of action;

• to provide maximum destruction against enemy supply and transportation facilities degrade his capacity to support his military operations in South Vietnam; and

• to offset adverse weather conditions extant and anticipated over the northernmost areas of North Vietnam which would limit TACAIR strikes.

By late September, as the bombing continued, the target list had been refined to a total of approximately sixty targets. Through September, October, and November, however, the operational commanders continued to eschew use of B-52s against these selected targets while concentrating B-52 attacks on logistics and interdiction targets located in the southern portion of North Vietnam.27 TACAIR assets utilizing LGBs continued to strike targets in and about Hanoi and Haiphong. By early October, North Vietnamese efforts had been stymied, and the Hanoi government was suing for peace. The Paris peace talks entered a phase of fruitful discussions. With North Vietnam appearing to be responding favorably toward a mutually satisfactory conclusion of the conflict, the JCS issued new orders that decreased substantially or totally restricted offensive air operations over North Vietnam. On 11 October, the JCS directed cessation of air strikes within a 10 nm radius of Hanoi. Simultaneously, maximum effort strikes were redirected against bridges and rail targets outside the restricted zone surrounding Hanoi to maintain military pressure on North Vietnam.

On 21 October, Dr. Kissinger flew to Saigon to discuss the general terms of the proposed agreement with the Saigon government, U.S. Ambassador Ellsworth Bunker, and Generals Fred C. Weyand (COMUSMACV) and John W. Vogt. Generals Weyand and Vogt objected to cessation of the bombing of North Vietnam, including the Hanoi/Haiphong area, until all terms of the agreement had been reached. Kissinger did not accept their recommendation, messaging the White House that all agreed with the general thrust of the agreement. At the direction of the White House, the JCS ordered CINCPAC, CINCSAC, and Seventh Air Force to "cease air operations of all types. . . [including] leaflet and psychological operations and naval gunfire operations north of 20°N commencing 23 October 1972. . . " Kissinger simultaneously announced that "We believe that peace is at hand. We believe an agreement is in sight…"28

Air operations did not cease entirely. Interdiction strikes continued, with emphasis on targets south of 19° N. For example, B-52s flew 848 sorties against logistic and interdiction targets in North Vietnam during November; on 22 November, the first B-52 was lost to a SAM in a strike against supply/storage areas near Vinh. Nonetheless, the bombing halt above 20° N provided the breathing spell sought by the North Vietnamese, who thereupon made the strategic decision to prolong the war in order to gain a military advantage which would lead to greater political concessions by the United States and South Vietnam in the Paris negotiations. They redoubled their air defenses in and around Hanoi/Haiphong while restoring their war-waging capabilities. By mid-December, for example, Hanoi had repaired its rail lines to China and adjusted its supply routing to compensate for the naval mine blockade. The restored rail lines were capable of handling 16,000 tons of supplies per day, or 2.5 times Hanoi’s needs. Simultaneous with the cessation of bombing north of 20° N, the North Vietnamese began to unravel the terms of settlement to which they had previously agreed. By early December, the agreement that had appeared so near five weeks earlier was in a shambles; the North Vietnamese had returned to their pattern of using the Paris meetings as a propaganda forum while engaging in a massive military buildup. Anticipating the possibility of a U.S. response with air power, they began to evacuate Hanoi and Haiphong while giving further emphasis to the air defense of those cities. President Nixon elected to preempt their military planning by restoring the bombing campaign north of 20° N. However, the desire for immediate effect was hampered by the adverse weather conditions prevailing over the Red River Valley, substantially impeding the use of TACAIR assets in a visual bombing mode. The planning of the previous five months provided the ability to strike selected targets regardless of the weather, while serving as an unequivocal display of U.S. resolve.29 Consequently, on 17 December, the JCS issued the following message to CINCPAC, CINCSAC, and subordinate operational commanders:








Although the operation named Linebacker II was essentially a continuation of the bombing campaign of the preceding eight months, which included earlier B-52 strikes in the Haiphong area, it was distinctive in two respects. Ever-increasing international and domestic pressure on the United States for resolution of the conflict mandated attainment of a certain level of damage to military targets within the shortest period of time, while adverse weather conditions dictated reliance on all-weather capabilities more than visual attack.31 The overall objective remained the same. However, whereas earlier Linebacker I efforts had the military purpose of widespread interdiction, Linebacker II concentrated on bombing targets located in the military-industrial center of North Vietnam.32

Targeting, including choice of weapon systems and rules of engagement, reflected the limited objectives of the campaign and the concern for avoidance of collateral civilian casualties and injury to U.S. POWs. The previously established criteria for B-52 employment were maintained: B-52s were used only against targets away from heavily populated areas or against targets of sufficient size to establish a desired mean point of impact (DMPI) that would minimize the likelihood that any part of the bomb train would fall outside the target. Where rural targets were near a village or villages, an axis of attack was designated that would avoid intersection of the bomb train with the villages.33 CINCSAC-imposed restrictions emphasized accuracy and assured destruction and minimization of incidental civilian casualties; constant verification, of course, 100 percent certainty of aiming points, and no maneuvering to avoid SAMs or enemy fighters from the initial point on the bomb run to the target—the latter requiring straight and level flight in a high-threat environment for approximately four minutes prior to bomb release.34 BDA of every target was ordered. These restrictions far exceeded the requirements of the law of war. However, they reflected valid military as well as political concerns. For example, SAC posited that the last requirement enhanced the ability to maintain B-52 cell integrity, which in turn maximized electronic countermeasures protection as well as accuracy of bomb delivery.

On 20 December, Linebacker II forces suffered the loss of six B-52s to enemy SAMs. A change of tactics, diversification by SAC of their previously utilized axis of attack, coupled with increased command attention to maintenance of B-52 cell integrity, and increased ECM were ordered to enhance aircraft survival. The previous excellent multiservice cooperation and coordination to overcome the SAM defenses were redoubled. However, it was clear to mission planners that the SAM threat had to be confronted directly. The B-52 sorties decreased from the near-100 of each of the first three days to thirty for each of the next four days as targeting intelligence commenced an intense search for the key or keys to the SAM defenses. B-52 assets were deployed in part to attack SAM sites located outside populated areas. The search continued through the 36-hour stand-down ordered by President Nixon for Christmas. As SAM storage areas were located, each was added to the list of targets and validation requested. One key was a SAM assembly plant in the immediate Hanoi area. The value of its destruction was inestimable; but weather conditions precluded use of precision guided munitions (PGM) or visual attack by TACAIR, and the target location prevented B-52 employment. In one of the more remarkable feats of the air campaign, the target was destroyed by 16 LORAN-guided F-4s bombing through solid overcast from 20,000 feet. Despite the fact that 48 SAMs were fired at the formation, all aircraft held their positions throughout the bomb run. No losses were suffered, and collateral civilian casualties and damage were determined to have been minimal.35

Destruction of the SAM defenses led to a marked change in the North Vietnamese attitude toward a return to meaningful peace negotiations.36 Linebacker II drew to a close after eleven days of intense bombing, flown in the face of equally intense defenses. The peace talks were renewed three days later, with formal discussions commencing on 8 January l973. Bombing up to 20°N continued until 15 January, when agreement for a Vietnam-wide cease-fire was reached.

From a military standpoint, Linebacker II was highly successful. In the face of some of the heaviest air defenses in history, selected targets had been destroyed with loss rates less than anticipated.37 Use of the all-weather capabilities of the B-52, F-l11, and other TACAIR had been justified in that there had been only 2½ days of weather permitting visual bomb delivery. But Linebacker II was notable from a political standpoint as well. "[The] object [of war] is to cause the other State to desist from the action or abandon the claim which is the cause of offense. In other words, a war is fought in order to bring about a change of mind in another State."38 The influence of Linebacker II on the North Vietnamese willingness to continue the war has been commented on at two levels. U.S. prisoners of war have attested to the reaction at the ground level in the reversal of attitude of their captors.39 One member of the U.S. delegation to the Paris peace talks related that "Prior to Linebacker II, the North Vietnamese were intransigent, buying time, refusing even to discuss a formal meeting schedule After Linebacker II, they were shaken, demoralized, anxious to talk about anything. The finally realized they were at war with a superpower. If there was bewilderment, it was with our reluctance to use that power earlier."40

Despite the unprecedented care taken to minimize collateral civilian casualties and collateral damage to civilian objects, the United States was castigated by the world press for what erroneously was believed to be the level of destruction being wrought over all of Hanoi.

Responsibility for this misperception lies with the White House. During the Linebacker I controversy over the alleged bombing of the dikes, the Department of State issued a detailed response to the North Vietnamese charges. In contrast, except for the release of a partial list of targets, the White House surrounded Linebacker II with a veil of secrecy which in large measure remains to this day.41 The North Vietnamese disinformation campaign about the bombing went unchallenged by the facts and abetted by the less-responsible side of the political process.

Some responsibility for the misunderstanding of Linebacker II lies in shoddy scholarship, particularly in the promiscuous use of terms and estimations where accurate information was available. Much of the subsequent error of fact was error of convenience. For example, more than two years after Linebacker II, syndicated columnist Marquis Childs complained of the "carpet bombing" in which "much of Hanoi was razed," leaving "nearly a thousand civilians dead or wounded" in the Hanoi "suburb of Thai Nguyen," a statement which errs on no less than six counts, despite information available in open sources.42 Critics have compared Linebacker II to the destruction of Coventry, Hamburg, Dresden, and Tokyo during World War II, and of Guernica during the Spanish Civil War. One university professor, writing in late 1981, declared that "The Christmas, 1972, bombing alone ravaged Hanoi and Haiphong with more tonnage than the Nazis dropped on Great Britain from 1940 through 1945," a statement that is patently false.43 This erroneous confusion of the facts has obscured the true criteria by which this campaign should be judged.

If Linebacker II is to be judged, it should be measured against the law of war, for those are the rules governing nations in their conduct of hostilities. Moreover, as the United States is a nation dedicated to rule by law, it is

essential to understand our rights and responsibilities under the law of war.

The law of war constitutes a delicate balancing of national security interests (expressed in legal terms as military necessity) against the desire of the United States and most members of the international community to limit to the extent practically possible the effects of war to those individuals and objects having a direct effect on the hostilities (which is expressed as the avoidance of unnecessary suffering by those not taking part in the conflict). The Air Force document on the law of war defines military necessity as justifying "measures of regulated force not forbidden by international law which are indispensable for securing the prompt submission of the enemy, with the least possible expenditures of economic and human resources."44 The compatibility of military necessity with the principle of war of economy of force is readily apparent in the Air Force’s definition of the latter: ". . . no more—or less— effort should be devoted to a task than is necessary to achieve the objective. . . . This phrase implies the correct selection and use of weapon systems, maximum productivity from available flying effort, and careful balance in the allocation of tasks."45 In contrast, unnecessary suffering has been defined to mean that "all such kinds and degrees of violence as are not necessary for the overpowering of the opponent should not be permitted to the belligerent."46 The concepts of military necessity and unnecessary suffering are weighed both in the target value analysis and target validation process as well as in force application once a target has been validated for attack.

Lawful targets include any object that by its nature, location, purpose, or use makes a contribution to a nation’s war effort and (correlatively) whose total or partial destruction, capture, or neutralization affects the enemy’s capability to resist and lowers his determination to fight. The inherent nature of an object is not controlling; its value to the enemy or the perceived value of its destruction is the determinant. Lawful targets are not limited to military facilities and equipment but may include economic targets (including industrial targets, whether directly war-supporting or not or used for activities such as export or import), geographic targets, transportation, power, and communications systems, and political targets. A lawful target maybe at tacked whatever its location, and targets do not become immune from attack simply because they arc located in population centers. There were proposals before World Wars I and II to reduce the attractiveness of urban centers as aerial targets, such as the removal of all military targets from cities. These proposals were rejected as impractical, as nations do not go about city planning over decades in contemplation of war. Some legitimate targets, such as transportation and energy facilities, support a nation’s economy as a whole, in peace or war. Other objects are used jointly or can be transformed from purely civilian to purely military use with no effort. Moreover, workers must live near the "military target" in which they are employed. What is prohibited is the intentional attack of the civilian population per se or individual civilians not taking part in the conflict, or the employment of military force in such a manner as to result in excessive collateral civilian casualties or excessive collateral damage to civilian objects. Historically, this standard has enjoyed a high threshold—condemning only collateral civilian casualties so excessive as to be tantamount to the intentional attack of the civilian population or to a total disregard for the safety of the civilian population.47 With rare exception, such as was exemplified by the balancing that occurred in planning the attack of the Lang Chi hydroelectric facility, this test of proportionality has not been applied to individual targets, due to the myriad factors within the control of the defender which affect execution of an attack. Such latitude also recognizes the movement of civilians on the battlefield and the necessity for decision-making in the fog of war. It does not include civilian injury or death directly attributable to enemy action such as civilians killed by the crash of an attacking aircraft downed by enemy air defenses or the injury or death of civilians used by the defender to shield a lawful target from attack. Nor does it include civilians injured or killed while working in a lawful target, such as an enemy power plant, or civilians killed or injured taking part in the hostilities, such as manning an antiaircraft position. The latitude provided is qualified by the expectation that military commanders will make a good-faith effort to minimize collateral civilian casual consistent with reasonable security expectations for their own forces. The measure, however, is not one of tons of bombs dropped, nor number of sorties flown, but the degree of lateral civilian casualties and damage to civilian objects directly attributable to an attacker, taking into consideration actions by the defender (including the intensity of the defenses). Inasmuch as the defenses faced in Linebacker II have been described as among the most intense in air power history and accepting the critics’ choices for comparison, the accompanying chart provides testimony to the adherence of Linebacker II forces to the law of war in the execution of their assigned missions.

There was collateral damage during Linebacker II, and Hanoi did its utmost to exploit the propaganda value of it. But the damage was limited, particularly when compared to the aerial bombing of World War II or the North Vietnamese artillery and rocket bombardments of An Loc, Hue, Quang Tri, and other cities of South Vietnam during its Easter offensive. Of the principal examples of collateral damage by Linebacker II forces, one of the more renowned surrounds damage to Bach Mai Hospital. Bach Mai Hospital is a 940-bed facility located 1.8 miles from the center of Hanoi, and less than 500 meters from the nearest points of the military complex of Bach Mai airfield and Bach Mai military storage facility. The former was not capable of handling jet aircraft but served as the command and control headquarters for the North Vietnamese air defense system; it was for the North Vietnamese what RAF Fighter Command Headquarters at Bentley Priory was for Great Britain during the Battle of Britain. As such, it was a valuable military target. With the exception of Bach Mai Hospital, the military complex is surrounded by uninhabited marshlands. However, because of its proximity to the hospital, Bach Mai airfield was not attacked until the waning days of Rolling Thunder. During Linebacker I, improved weapons and delivery platforms resulted in the military complex’s being struck on several occasions. During Linebacker I and II, mission parameters for attack of the Bach Mai military complex were established to minimize the likelihood of collateral damage to Bach Mai Hospital. Although it frequently housed antiaircraft positions to defend the military complex, a violation of the law of war, Bach Mai Hospital never was nominated for attack.52

In the course of Linebacker II operations on 21 December, bombs were dropped on Bach Mai Hospital. The Hanoi government reported that the "main building and some other sections have been demolished. . . . Many patients,

physicians and nurses [were] killed or wounded. Today, practically nothing remains." Subsequently, it acknowledged that the hospital had been evacuated of patients and medical staff before Linebacker II and that only care-taker personnel had been on hand at the time the hospital had been struck. On 2 January 1973, the Department of Defense confirmed accidental damage to the hospital. Aerial photographic coverage and investigation suggested that the hospital was hit by a portion of the bomb train of a B-52 bracketed and struck by two SAMs at the instant it reached its bomb release point, causing it to splay its bombs as the pilot lost control. Similar hits resulted in damage along the residential Kham Thien street in Hanoi, which Hanoi showed to all visitors as evidence of U.S. "indiscriminate" bombing. Aerial photographs were more discerning in showing the limited nature of incidental damage.53

Minor collateral damage occurred at Gia Lam International Airport, Hanoi textile plant on 8 March, and in the An Duong/Nghia Dong area north of Hanoi. The Hanoi government alleged that the Gia Lam terminal had been "leveled." Poststrike photography revealed that a small VIP terminal had been hit, but damage to the main terminal was so minor that U.S. prisoners of war repatriated through Gia Lam observed no damage to the terminal, and some meetings of the postwar Four Party Joint Military Team overseeing the cease-fire were held in the terminal, which showed no signs of damage or recent repair.

By North Vietnamese count, 1318 civilians died during Linebacker II. The figure does not distinguish between civilians not taking a direct part in the hostilities and civilians killed while working in lawful targets or taking part in the conflict. Nor does the figure differentiate between those civilians killed by errant bombing caused by actions of the defender, as occurred in the bombs dropped on Kham Thien street, or civilians killed by North Vietnamese SAMs or AAA projectiles which, having missed their targets, plummeted to the ground. Hanoi fired more than 1000 SAMs at Linebacker II forces, showing little or no regard for the safety of its own people in their firing, and the area in and around Hanoi and Haiphong became an impact area for North Vietnamese high-explosive ordnance. Undoubtedly, many of the 1318 civilian deaths can be attributed to these North Vietnamese defenses.

Measured against the only standard accepted in principle by nations—the law of war—and accepting Hanoi’s casualty figure without qualification, Linebacker II is unprecedented in its minimization of collateral damage and collateral civilian casualties when compared with the intensity of effort against legitimate targets.

For a Little more than a century, the nations of the world have undertaken to find ways to ameliorate the suffering of individuals not taking a direct part in armed conflict. The principal vehicle for this effort has been a series of multilateral treaties, commonly known as the law of war. Their obligations apply equally to all nations, in all conflicts. Some depend on reciprocity, while others do not. As is true of all laws, portions of the law of war have worked extremely well, while other parts have not worked well at all. Nonetheless, the law of war recognizes that the business of the military in war is killing people and breaking things.54 The law of war reflects a delicate balance between humanitarian ideals and the national security interests of each belligerent, the latter serving as the lowest common denominator both in negotiations and implementation of law of war treaties. In many circumstances the minimum standard of conduct may also represent the maximum limitation acceptable to belligerents if each hopes to achieve a successful end to the conflict.

In Rolling Thunder, apparent ignorance of the law of war at the national level placed unreasonable burdens on U.S. forces to their substantial detriment, which the enemy was quick to exploit. The campaign drew to a close just as some of these political shackles were being removed and the campaign was beginning to realize some success. Linebacker I and Linebacker II were conducted with myriad advantages over Rolling Thunder: improved weapons, weapon systems, targeting, operational flexibility, tactics, and, undoubtedly most important, with the will on the part of the nation’s leaders to utilize military force as necessary to achieve campaign objectives. Both Linebacker campaigns were also conducted with an acute awareness by the military of its responsibilities under the law of war, with mission parameters well within the prohibitions of the law. Although unprecedented in the degree of precaution taken by an attacker to minimize collateral injury to the civilian population of an enemy, each campaign was successful in attaining its objectives. But the White House decision not to respond to the unfounded allegations of "indiscriminate bombing" denied to those who risked their lives recognition for the professional manner in which they discharged their responsibilities.

Washington, D.C.




1. Lyndon B. Johnson, The Vantage Point (New York, 1971), pp. 515-29; W. W. Rostow, The Diffusion of Power (New York, 1972), pp. 522-23.

2. Henry A. Kissinger, White House Years (Boston, l979), p. 1109.

3. For a description of Rolling Thunder, see W. Hays Parks, "Rolling Thunder and the Law of War," Air University Review, January-February 1982, pp. 2-23.

4. Actually, this operation was called Freedom Train until 9 May, when it was renamed Linebacker I. The initial Linebacker I attacks of 10 May were named Rolling Thunder Alpha because the new name had not filtered down to the operational commands. The mining operations were called Pocket Money.

5. There was at least one recommendation for a counterinvasion. See E. W. Besch, "Amphibious Operation at Vinh," Marine Corps Gazette, December 1982, pp. 54-60.

6. Johnson, p. 241.

7. Richard M. Nixon, The Memoirs of Richard Nixon (New York, 1978), pp. 606-7. (Emphasis in original.)

8. Ibid., p. 606.

9. Conversation with General John W. Vogt, USAF (Ret), 1 July 1982.

10. Confirmed, suspect, or possible targets for informational and planning purposes but not validated for attack.

11. In the case of Linebacker land Linebacker II, targets authorized by the NCA (through the JCS) for attack.

12. Political targets that support military action, such as agencies that provide command, administrative, or logistic support for military operations, are lawful targets. Even if attacks on them would be otherwise lawful, political targets frequently receive protection from attack. In World War II, for example, the USAAF was directed to avoid damaging the Imperial Palace in Tokyo during air raids on that city. (Air Force Pamphlet 110-34, Commander’s Handbook on the Law of Armed Conflict (1980), para 2-5.) In the course of Linebacker II, the Lao Dong party headquarters in Hanoi was struck by a laser guided bomb which had broken its guidance. The Hanoi regime, convinced that the attack was intentional, voiced no objection to the strike (apparently not wishing to acknowledge its success) but took serious steps to indicate its willingness to return to the negotiating process. (Conversation with General Vogt.)

13. Linebacker I maintained the route package system of Rolling Thunder, numbered 1-VI running north to south from the DMZ. The Navy reassumed responsibility for Route Packages II, III, IV, and VIB; the Air Force, for V and VIA. COMUSMACV controlled bombing in Route Package I.

14. Part of the contrast in law of war application appears to have been the result of the presence on the staff of the Chairman of the Joint Chiefs of Staff of a judge advocate with a knowledge of the law of war. Previous judge advocates in the Chairman’s office generally restricted themselves to advice on legislative and budget matters.

15. See Colonel Delbert Corum et al., The Tale of Two Bridges (Washington, 1976), for a detailed description of the attacks on the Thanh Hoa bridge. See also Peter B. Mersky and Norman Polmar, The Naval Air War in Vietnam (Annapolis, 1981), pp. 107, 109; and Henry W. Brandli, "The Use of Meteorological Satellites in Southeast Asia Operations," Aerospace Historian, Fall 1982, pp. 172-75. The first-generation PGM or so-called smart bombs were not the panacea weapon envisioned by many. In the course of Linebacker I and II, several errant LGBs caused incidental damage, which created a certain degree of diplomatic embarrassment for the United States. For example, on II October 1972, an LGB struck the French Embassy in Hanoi. Dr. Kissinger, at the time involved in the Paris peace talks, reported that the incident did not endear the U.S. with its French hosts; Henry Kissinger, Years of Upheaval (Boston, 1982), pp. 24-25. On 21 December, an LGB intended for the Hanoi railroad station struck the excusado at the nearby Cuban chancellery. The author’s wife, a former Cuban refugee, believes this was the smartest bomb of the war, a view undoubtedly shared by those POWs tortured by Cubans sent by Fidel Castro to assist the North Vietnamese with propaganda exploitation of the U.S. POWs.

16. Seymour M. Hersh, "Dikes in Hanoi Represent 2,000-Year Effort to Tame Rivers," New York Times, July 14, 1972, p. 6.

17. Sir Charles Webster and Noble Frankland, The Strategic Air Offensive against Germany, volume II (London, 1961), pp. 168-69; Helmut Euler, Als Deutschlands Diimme brachen (Stuttgart, 1978); John Sweetman, Operation Chastise (New York, 1982). Albert Speer noted that the 617 raid, "employing just a few bombers…came close to a success which would have been greater than anything they had achieved hitherto with a commitment of thousands of bombers." His efforts to get the Luftwaffe to undertake similar attacks of Russian hydroelectric plants was unsuccessful. Inside the Third Reich (London, 1970), pp. 280-83.

18. Webster and Frankland, vol. III (London, 1961), pp. 244-48; Kit C. Carter and Robert Mueller, editors, The Army Air Force in World War II: Combat Chronology (Washington, 1973), p. 482.

19. "The Attack on the Irrigation Dams in North Korea," Air University Quarterly Review, Winter 1953-54, pp. 40-61; Robert F. Futrell, The United Stated Air Force in Korea (New York, 1961), pp. 623-29.

20. Pentagon Papers (Gravel Edition), vol. IV(Boston, 1971), p. 43.

21. Bernard Gwertzman, "U.S. Issues Report to Rebut Charges on Dike Bombings," New York Times, July 29, 1972, p. 1; and "Text of Intelligence Report on Bombing of Dikes in North Vietnam Issued by State Department," New York Times, July 29, 1972, p. 2. Because of a House of Representatives resolution sponsored by Congressman Paul N. McCloskey, Jr. (R-Cal.), the House Armed Services Committee convened a formal investigation to look into the dike-bombing allegations. A JCS representative appeared before the full HASC. His presentation was so thorough that he was interrupted midway through it and the investigation summarily dismissed. The United States was able to rebut these charges only through substantial expenditure of valuable national assets and risk of life by U.S. military personnel. Thousands of man-hours were diverted from the war effort to respond to the allegations, raising a question for future military operations as to the degree to which the military must plan to respond to spurious charges.

22. Cluster bomb units (CBUs) or munitions were criticized by North Vietnam and supporters such as Sweden as being "illegal" during Linebacker. The legality of CBU was considered by an ad hoc committee on conventional weapons during the Swiss-convened Diplomatic Conference on the Reaffirmation and Development of International Humanitarian Law Applicable in Armed Conflicts, which met in Geneva from 1974 to 1977, and at the United Nations-sponsored Conference on Prohibitions of Restrictions on the Use of Certain Conventional Weapons Which May Be Deemed to Be Excessively Injurious or to Have Indiscriminate Effects, which met in Geneva from 1978 to 1980. CBUs were not determined to be "illegal," and neither produced a treaty containing any prohibition or restriction of CBUs.

The controversy surrounding CBU use by Israel in its war against the PLO in Lebanon in 1982 was limited to the question of whether U.S. -manufactured CBUs were employed by Israel contrary to U.S. -Israeli arms transfer agreements. Their use against PLO military positions in built-up areas not only was consistent with the law of war but probably resulted in less incidental damage to surrounding civilian structures than alternative weapons (such as high explosive bombs), a point acknowledged by the U.S. press. See, for example, the editorial in the Washington Post, "Cluster of Difficulties," July 21, 1982, p. A22. The reader is left to speculate as to whether the U.S. press would have been quite so charitable in its support for the legality of CBU had the issue been addressed during Linebacker.

23. For example, in late July, former Attorney General Ramsey Clark traveled to Moscow and Hanoi as a member of an "international commission" sponsored by the Stockholm-based International Commission of Inquiry into United States Crimes in Indochina investigating the North Vietnamese allegations.

24. Seymour M. Hersh, "War Foes See No Evidence of Deliberate Dike Attacks," New York Times, June 24, 1972, p. 3.

25. As noted by Kissinger, White House Years, pp. 1098, 1111. Dr. Kissinger states that between 8 May and 12 August, 42 percent of all strikes against primary targets in North Vietnam were canceled because of weather. The problem was not unique to Linebacker I. See, for example, "The Rain Makes the Flak Worse," The Economist, October 14, 1967, p. 141; and General William W. Momyer, Airpower in Three Wars (Washington, 1978), pp. 175-83. One source concludes that Hanoi became intransigent because of the impending northeast monsoon season, feeling it would seriously impede TACAIR attacks if there was a resumption of bombing. R. Frank Futrell et al., Aces and Aerial Victories (Washington, 1976), p. 16.

26. For example, the Yen Vien railroad yard, which included classification, relay, and station yards; a service area and turning wye; and large approach area with holding spur, measured 5200 feet by 1400 feet and had only two small villages within one nm of the outer edges of the target, or more than two nautical miles from the desired mean point of impact. Gia Lam railroad yard measured 4400 by 2250 feet; Thai Nguyen railroad yards, 13,300 by 1900 feet; and Hanoi POL storage, 4000 by 4000 feet.

27. B.52s flew 337 sorties in July, 560 in August, 411 in September, and 502 in October against targets in North Vietnam, which continued to be secondary to the Arc Light support being provided in South Vietnam.

28. Kissinger, White House Years, p. 1399. The Saigon meeting was described by General Vogt at the Military Classics Seminar, Fort Myer, Virginia, 16 April 1982.

29. Kissinger, White House Years, pp. 1446-50.

30. Message, JCS to CINCPAC 17001 OZ Dec 72, Subj: Linebacker II Operations. Declassified by OJCS DJSM-340-80, 15 February 1980. Certain targets on the JCS target list were designated for LGB attack only.

31. From a targeting and weaponeering standpoint, B-52s were not the optimum weapon system for many of the targets; TACAIR with or without PGM would have been the preferred weapon platform in many cases had operational commanders been able to choose the time and weather. For example, visual TACAIR strikes with conventional "dumb" bombs or with PGM would have been preferable to B-52s for attack of the Duc Noi warehouse storage area had a choice been available, including acceptable weather.

32. A total of 103 targets were authorized for attack. Thirty-one were in the vicinity of Hanoi; nineteen were near Haiphong. The remaining fifty-three were more than ten nautical miles from the geographic centers of Hanoi and Haiphong. Twenty-seven of the Hanoi targets were attacked, fifteen of the Haiphong targets, and twenty of those outside the Hanoi/Haiphong area.

33. For example, the Duc Noi warehouse storage area, seven miles north of Hanoi on the NW rail line, was struck on 28 December by B-52s flying on a course parallel to rather than intersecting two small villages located within one nautical mile of the outer edges of the target. Poststrike BDA photographs clearly reflect the axis of attack.

34. Brigadier General James R. McCarthy and Lieutenant Colonel George B. Allison, Linebacker II: View from the Rock (Washington, 1979), pp. 46-47, 50, 64, 68.

35. Conversation with General Vogt; Admiral Thomas H. Moorer, 15 September 1982.

36. General Vogt. Ambassador George H. Aldrich, Conference on International Humanitarian Law, American University, 12 March 1982. Ambassador Aldrich was Deputy Legal Adviser, Department of State, and one of Dr. Kissinger’s principal assistants in the Paris negotiations. The connection of SAM destruction to the negotiators was not so clear to mission planners, nor was the degree of neutralization so certain. As a result, the support package for the 26 December raid was the largest of Linebacker II and the target system struck among the most varied.

37. Linebacker If loss rates were 2 percent, as compared to 19 percent for the Regensburg-Schweinfurt attack of 14 October 1943 and 30 percent for the 1 October 1943 raid on Ploesti. McCarthy and Allison, citing Thomas M. Coffey, Decision over Schweinfurt (New York, 1977), p. 332, and James Dugan and Carroll Stewart, Ploesti (New York, 1962), p. 222. Anticipated B-52 losses were three percent. "Tragedy of Linebacker II: The USAF Response," Armed Forces Journal International, August 1977, p. 24.

38. J. M. Spaight, AIr Power and War Rights, third edition (London, 1947), p. 2.

39. John G. Hubbell, P.O. W. (New York, 1976), pp.589-93; Rear Admiral Jeremiah A. Denton, Jr., When Hell Was in Session (New York, 1976), pp. 231-32; Colonel Robinson Risner, The Passing of the Night (New York, 1973), pp. 236-38; and Captain James A. Mulligan, The Hanoi Commitment (Virginia Beach, 1981), pp. 266-76. The North Vietnamese alleged during the course of Linebacker II that the Hanoi Hilton, which housed many of the U.S. prisoners of war, had been bombed "with many casualties," but former POWs have told me that the only danger during Linebacker II, which they describe as "the greatest show on earth," was from eye strain trying to watch U.S. efforts.

40. Ambassador Aldrich noted that "Once the Christmas bombing was over and they returned to the table, the atmosphere, their attitudes were 180 degrees different." Ambassador Aldrich, supra note 35. This view is shared by Dr. Kissinger in White House Years, pp. 1458-61. In early February 1973, Dr. Kissinger passed through Saigon en route to Hanoi, filled with trepidation regarding his upcoming confrontation with the North Vietnamese in Hanoi. On his return from Hanoi, Dr. Kissinger observed that the North Vietnamese had greeted him as if he were their longest and dearest friend. General Vogt, supra note 27. A more subdued but substantially similar account is related by Dr. Kissinger in Years of Upheaval, pp. 23-28.

41. A point elaborated on by Ambassador Martin F. Hetz in The Prestige Press and the Christmas Bombing, 1972 (Washington, 1980). See also Kissinger, White House Years, pp. 1448-49. Part of the reluctance of President Nixon to confront the press undoubtedly lay in the then-rising specter of Watergate; but part also undoubtedly lay in the skepticism regarding the likelihood that the press would be willing to offer a balanced account (e.g., see Lieutenant Colonel Gerald S. Venanzi, USAF, "Democracy and Protracted War: The Impact of Television," in this issue of the Review, p. 58. Even where information was provided, it was received by some who considered it barbaric for the United States to utilize lawful means and methods of warfare to interfere with North Vietnamese barbarism, almost in a sense of frustration that the United States and South Vietnam might win. For example, during the conduct of Linebacker II, a representative of the Joint Chiefs of Staff briefed the House Armed Services Committee after each day of operations. The JCS took great pains to illustrate through photographs the extremes being taken at every level of command to minimize risk to the civilian population of North Vietnam, much to the chagrin of those members of the HASC who opposed the bombing. A wrap-up briefing was provided in January 1973, after conclusion of Linebacker II. During the briefing a photograph was flashed on the screen showing damage in a residential section of Hanoi. A new member of the HASC seized upon the occasion to castigate the briefer for what appeared to be erratic bombing, demanding of the briefer that he explain the circumstances surrounding the damage. The briefer responded: "I regret. . . to say that the damage was caused by the crash of one of our B-52 aircraft after being hit by a North Vietnamese SAM, with the loss of the entire crew." The congressperson was not to be denied, however, as she screamed: "Well, dammit, General! Can’t you teach your pilots to crash somewhere else?" (Related to me by an individual who was present at that hearing.)

42. "Sky Writing and Carpet Bombing," Washington Post, April 29, 1975, p. A 15. His column was forcefully rebutted in a letter to the editor by Admiral Thomas H. Moorer, USN (Ret), who was Chairman of the Joint Chiefs of Staff during Linebacker land Linebacker II. Most journalists reviewing available evidence had concluded by early 1973 that Hanoi had neither been "razed" nor "carpet bombed." For example, see Drew Middleton, "Hanoi Films Show No ‘Carpet Bombing’," New York Times, May 2, 1973, p. 2. Dr. Kissinger notes the minimal damage to civilian areas in Hanoi in Years of Upheaval, p. 24. See also Guenter Lewy, America in Vietnam (New York, 1978), pp. 413-14.

43. H. Bruce Franklin, "Teaching the Vietnam War: Who Won, and Why?" The Chronicle of Higher Education, November 4, 1981, p. 64. The 15,287.4 tons of Linebacker II is a far cry from the 40,885 tons of bombs dropped by the Luftwaffe during the Battle of Britain alone. Francis K. Mason, Battle over Britain (London, 1969), p.615. A total of 71,270 tons of bombs and rockets fell on the British Isles during World War II. Terence H. O’Brien, Civil Defence (London, 1955), p. 680.

44. Air Force Pamphlet 110-31, International Law—The Conduct of Armed Conflict and Air Operations, 1976, paragraph l-3a(l).

45. Air Force Manual I-I, Functions and Basic Doctrine of the United States Air Force, 1979, p.5-S.

46. J. Lauterpacht, editor, International Law, vol. II, Disputes, War and Neutrality (London, 1952), p. 72.

47. This definition has been clarified as the result of an exchange between Major General John P. Wolfe, former Judge Advocate General of the Canadian Forces, and me published in Air University Review, September-October 1982, pp. 82-83.

48. Mason, p. 615.

49. Figure based on retraction by David Irving, Times (London), July 7, 1966, p. 13. Irving in The Destruction of Dresden (New York, 1963), p. 11, erroneously put the figure at "more than 135,000."

50. The figure is derived from analysis of BDA coverage of all targets and the damage on Kham Thien street, in Ira, even though the latter legally would not be the exclusive responsibility of the attacker, and doubled to allow a large margin of error.

51. "North Vietnam Says 1,318 Dead in the Raids on Hanoi," New York Times, January 5, 1973, p. 3.

52. Article 21 of the 1949 Geneva Convention Relating to the Protection of the Wounded and Sick ("GWS") provides for the discontinuance of protection for a hospital when it is used for "acts harmful to the enemy." It also is noted that neither Bach Mai Hospital nor any of the prisoner-of-war camps in which U.S. and allied personnel were held were marked for identification to avoid inadvertent attack, as required by Article 42 of the GWS, Article 19 of the Geneva Convention Relative to the Protection of Civilian Persons in Time of War, or Article 23 of the Geneva Convention Relative to the Treatment of Prisoners of War. Both the United States and North Vietnam were parties to these treaties throughout the war.

53. Despite the North Vietnamese repudiation of their claim of extensive casualties at Bach Mai Hospital, their original allegation was repeated by CBS’s "60 Minutes" in a segment broadcast on 14 November 1982. Although their error was brought to their attention and an original source proffered to verify the information, CBS elected to make neither a clarification nor correction.

54. A poignant but accurate statement I attribute to Colonel Zane E. Finkelstein, USA. Colonel Finkelstein served as one of the legal advisors to the Chairman of the Joint Chiefs of Staff during Linebacker I and Linebacker II.


W. Hays Parks (B.A., J.D., Baylor University) is Chief, International Law Branch, International Affairs Division, in the Office of The Judge Advocate General of the Army, Washington, D.C. He has served as a Marine infantry officer and judge advocate in Vietnam and is a lieutenant colonel in the United States Marine Corps Reserve. Parks has lectured on international law and the law of war at the National, Army , and Naval War Colleges, the Royal Air Force College, and the Marine Corps Amphibious Warfare School and Command and Staff College. He is a previous contributor to the Review.


The conclusions and opinions expressed in this document are those of the author cultivated in the freedom of expression, academic environment of Air University. They do not reflect the official position of the U.S. Government, Department of Defense, the United States Air Force or the Air University.

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