Operation Rolling Thunder

Operation Rolling Thunder was the title of a gradual and sustained US 2nd Air Division (later Seventh Air Force), US Navy, and Republic of Vietnam Air Force (VNAF) aerial bombardment campaign conducted against the Democratic Republic of Vietnam (North Vietnam) from 2 March 1965 until 2 November 1968, during the Vietnam War.

The four objectives of the operation (which evolved over time) were to boost the sagging morale of the Saigon regime in the Republic of Vietnam, to persuade North Vietnam to cease its support for the communist insurgency in South Vietnam without actually taking any ground forces into communist North Vietnam, to destroy North Vietnam's transportation system, industrial base, and air defenses, and to cease the flow of men and materiel into South Vietnam. Attainment of these objectives was made difficult by both the restraints imposed upon the U.S and its allies by Cold War exigencies and by the military aid and assistance received by North Vietnam from its communist allies, the Soviet Union and the People's Republic of China (PRC).

The operation became the most intense air/ground battle waged during the Cold War period; indeed, it was the most difficult such campaign fought by the U.S. Air Force since the aerial bombardment of Germany during World War II. Supported by communist allies, North Vietnam fielded a potent mixture of sophisticated air-to-air and ground-to-air weapons that created one of the most effective air defenses ever faced by American military aviators.

Background
In response to President Ngo Dinh Diem's abrogation of the 1956 reunification election and suppression of communists during the late 1950s, Hanoi had begun sending arms and material to the guerrillas of the National Front for the Liberation of South Vietnam (NLF), who were fighting an insurgency to topple the American-supported Saigon government. To combat the NLF and to shore up the government in the south, the U.S. initially delivered monetary aid, military advisors, and supplies. Between 1957 and 1963, the U.S. found itself committed, through its acceptance of the policy of containment and belief in the domino theory, to defending South Vietnam from what it saw as expansive communist aggression. During the Vietnam War, an estimated 643,000 tons of bombs were dropped at the approximated cost of $900 million.

U.S. policy was for a time dictated by its perception of improvement in the Saigon government. No further commitment by the Americans would occur without tangible proof of the regime's survivability. Events in Vietnam, however, outraced this policy. By the beginning of 1965, it was stood upon its head – without further American action the Saigon government could not survive.

Questions then arose among the U.S. administration and military leadership as to the best method by which Hanoi (the perceived locus of the insurgency) could be dissuaded from its course of action. The answer seemed to lie in the application of air power. By 1964 most of the civilians surrounding President Lyndon B. Johnson shared the Joint Chiefs of Staff's collective faith in the efficacy of strategic bombing to one degree or another. They reasoned that a small nation like North Vietnam, with a tiny industrial base that was just emerging after the First Indochina War, would be reluctant to risk its new-found economic viability to support the insurgency in the south. Constantly affecting this decision-making process were fears of possible counter moves or outright intervention by the Soviet Union, the PRC, or both. The civilians and the military were divided, however, on the manner of affecting Hanoi's will to support the southern insurgency. The civilians thought in terms of changing the regime's behavior while the military men were more concerned with breaking its will.

In August 1964, as a result of the Gulf of Tonkin Incident, in which U.S. naval vessels claimed to have been attacked by North Vietnamese patrol boats, President Johnson ordered retaliatory air strikes (Operation Pierce Arrow) launched against the north. This did not, however, satisfy the military chiefs, who demanded a wider and more aggressive campaign.

Implementation
By the end of August, the Joint Chiefs had drawn up a list of 94 targets to be destroyed as part of a coordinated eight-week air campaign against North Vietnam's transportation network. Bridges, rail yards, docks, barracks and supply dumps were all targeted. Johnson, however, feared that such a campaign might trigger a direct intervention by Chinese or Soviets, which might, in turn, cascade into a world war. With McNamara's support, the president refused to endorse such an unrestricted bombing campaign.



Instead, the U.S. launched more "tit-for-tat" airstrikes in retaliation for a 7 February 1965 NLF attack at Pleiku (Operation Flaming Dart) and for a bomb attack against an American enlisted men's billet at Qui Nhon on the 10th (Operation Flaming Dart II). These small-scale operations were launched against the southern region of the country, where the bulk of North Vietnam's ground forces and supply dumps were located.

Surrendering to continued NLF advances and pressures from the Joint Chiefs, Johnson formally authorized a sustained bombing program, codenamed Rolling Thunder, which would not be tied to North Vietnamese actions. Rolling Thunder called for an eight-week air campaign consistent with the restrictions that Johnson and Secretary of Defense Robert S. McNamara had imposed upon it. If the insurgency continued "with DRV support, strikes against the DRV would be extended with intensified efforts against targets north of the 19th parallel."

It was believed that selective pressure, controlled by Washington, combined with diplomatic overtures, would prevail and compel Hanoi to end its aggression. The military was still not satisfied, since, for the time being, the bombing campaign was to be limited to targets below the 19th parallel, each of which would have to be cleared individually by the president and McNamara.

The first mission of the new operation was launched on 2 March against an ammunition storage area near Xom Bang. On the same day, 19 VNAF A-1 Skyraiders struck the Quang Khe Naval Base. The Americans were shocked when six of their aircraft were shot down during the mission. Five of the downed crewmen were rescued, but it was a portent of things to come.

Strategic persuasion
In keeping with the doctrine of "gradualism", in which threatening destruction would serve as a more influential signal of American determination than destruction itself, it was better to hold important targets "hostage" by bombing trivial ones. From the beginning of Rolling Thunder, Washington dictated which targets would be struck, the day and hour of the attack, the number and types of aircraft and the tonnages and types of ordnance utilized, and sometimes even the direction of the attack. Airstrikes were strictly forbidden within 30 nmi of Hanoi and within ten nautical miles (19 km) of the port of Haiphong. A thirty-mile buffer zone also extended along the length of the Chinese frontier. According to Air Force historian Earl Tilford:

"Targeting bore little resemblance to reality in that the sequence of attacks was uncoordinated and the targets were approved randomly – even illogically. The North's airfields, which, according to any rational targeting policy, should have been hit first in the campaign, were also off-limits."

Although some of these restrictions were later loosened or rescinded, Johnson (with McNamara's support) kept a tight rein on the campaign, which continuously infuriated the American military commanders, right-wing members of Congress, and even some within the administration itself. One of the primary objectives of the operation, at least to the military, should have been the closure of Haiphong and other ports by aerial mining, thereby slowing or halting the flow of seaborne supplies entering the north. President Johnson refused to take such a provocative action, however, and such an operation was not implemented until 1972. There was also little consultation between Johnson and the military chiefs during the target selection process. Even the Chairman of the Joint Chiefs, Army General Earl G. Wheeler, was not present for most of the critical discussions of 1965 and participated only occasionally thereafter.

The majority of strikes during Rolling Thunder were launched from four Air Bases in Thailand: Korat, Takhli, Udon Thani, and Ubon. The aircraft would refuel from aerial tankers over Laos before flying on to their targets in the DRV. After attacking their targets (usually by dive-bombing) the strike forces would either fly directly back to Thailand or exit over the relatively safe waters of the Gulf of Tonkin. It was quickly decided that, in order to limit airspace conflicts between Air Force and Naval strike forces, North Vietnam was divided into six target regions called "Route Packages", each of which was assigned to either the Air Force or Navy and into which the other was forbidden to intrude.

Navy strikes were launched from the aircraft carriers of Task Force 77, cruising off the North Vietnamese coast at Yankee Station. Naval aircraft, which had shorter ranges (and carried lighter bomb loads) than their Air Force counterparts, approached their targets from seaward with the majority of their strikes flown against coastal targets.

On 3 April the Joint Chiefs persuaded McNamara and Johnson to launch a four-week attack on North Vietnam's lines of communications, which would isolate that nation from its overland sources of supply in the PRC and the Soviet Union. About one-third of the north's imports came down the northeast railroad from the PRC, while the remaining two-thirds came by sea through Haiphong and other ports. For the first time in the campaign, targets were to be chosen for their military, rather than their psychological significance. During the four weeks, 26 bridges and seven ferries were destroyed. Other targets included the extensive North Vietnamese radar system, barracks, and ammunition depots.

The panhandle of southern North Vietnam, however remained the primary focus of operations and total sorties flown there rose from 3,600 in April to 4,000 in May. Slowly moving away from the destruction of fixed targets, "armed reconnaissance" missions, in which small formations of aircraft patrolled highways, railroads, and rivers, searching for targets of opportunity, were authorized. These missions increased from two to 200 sorties per week by the end of 1965. Eventually, armed reconnaissance missions would constitute 75 percent of the total bombing effort, in part because the system through which fixed targets were requested, selected, and authorized was so complicated and unwieldy.

Changing priorities and POL strikes
If Rolling Thunder was supposed to "send signals" to Hanoi to desist in its actions, it did not seem to be working. On 8 April, responding to requests for peace negotiations, North Vietnamese Premier Pham Van Dong stated that they could only begin when: the bombing was halted; the U.S. had removed all of its troops from the south; the Saigon government recognized the demands of the NLF; and it was agreed that the reunification of Vietnam would be settled by the Vietnamese themselves. Ominously, on 3 April the North Vietnamese Air Force made its first appearance when American aircraft were attacked by NVAF MiG-17s.

The entire complexion of the American effort was altered on 8 March 1965, when 3,500 U.S. Marines came ashore at Da Nang, ostensibly to defend the southern airfields committed to prosecuting Rolling Thunder. The mission of the ground forces was expanded to combat operations and, from that point onward, the aerial campaign became a secondary operation, overwhelmed by troop deployments and the escalation of ground operations in South Vietnam. Until the third week of April, Rolling Thunder had enjoyed at least equal status with air missions conducted in the south. After that time, strikes that interfered with requirements for the southern battlefield were either cut back or cancelled.

By 24 December 1965, 170 U.S. aircraft had been lost during the campaign (85 Air Force, 94 Navy, and one Marine Corps). Eight VNAF aircraft had also been lost. Air Force aircrews had flown 25,971 sorties and dropped 32,063 tons of bombs. Naval aviators had flown 28,168 sorties and dropped 11,144 tons. The VNAF had contributed 682 missions with unknown ordnance tonnages.



U.S. reconnaissance discovered on 5 April 1966 that the North Vietnamese were constructing positions for what could only be surface-to-air missile (SAM) batteries. The Air Force and Navy then filed a joint appeal to Washington for permission to strike the sites, but they were refused since most of the sites were near the restricted urban areas. It came as no surprise when, on 24 July, an F-105 was shot down by a SA-2 Guideline missile. Three days later, a one-time strike was authorized against the two offending missile sites. The Americans, however, fell for an elaborate trap when the sites turned out to be dummies surrounded by anti-aircraft artillery defenses. One American pilot described the action which followed as "looking like the end of the world." Six of the strike craft were destroyed (two of the pilots were killed, one missing, two captured, and one rescued) during the debacle.

On 29 June 1966, airstrikes against the north's petroleum, oil, and lubricants (POL) storage areas were authorized by Johnson. The American military had advocated such strikes since the inception of the operation, believing that to deny North Vietnam its POL would cause its military effort to grind to a halt. The strikes at first appeared successful, destroying tank farms near Hanoi and Haiphong and leading the CIA to estimate that 70 percent of North Vietnam's oil facilities had been destroyed for the loss of 43 aircraft. The success proved only a short-term inconvenience for North Vietnam, however, since Hanoi had anticipated just such a campaign and had dispersed the majority of its POL stocks in 50-gallon drums across the length of the country. The POL attacks were halted on 4 September after U.S. intelligence admitted that there was "no evidence yet of any shortages of POL in North Vietnam."

Problems
Rolling Thunder exposed many problems within the American military services committed to it and tended to exacerbate others. A key interservice issue (and one which was not solved until 1968) was the command and control arrangement in Southeast Asia. The Air Force's 2nd Air Division (replaced by the Seventh Air Force on 1 April 1966) was ostensibly responsible for aerial operations over North and South Vietnam. It was subordinate, however, to MACV and its commander, U.S. Army General William C. Westmoreland, who tended to see his problems centered in the south. The U.S. Seventh/Thirteenth Air Force, based in Thailand (which carried out the majority of the Air Force's strikes in North Vietnam), had a dual command structure. It reported to the Seventh on operational matters and to the Thirteenth Air Force (whose headquarters was in the Philippines) for logistical and administrative concerns. These command and control complexities grew even more tangled with the division of the aerial effort into four competing operational areas (those in South Vietnam, North Vietnam, and Laos (both north and south).

The Navy's Task Force 77 took its orders via 7th Fleet from CINCPAC, a Navy admiral based in Honolulu, through his subordinate, the Air Force commander of Pacific Air Forces (PACAF). Due to their influence, the Navy could not be persuaded to integrate its air operations over North Vietnam with those of the Air Force. General William Momyer, commander of the Seventh, had the impression that CINCPAC and PACAF wanted to keep the Thai-based aircraft out of his hands. "By denying Momyer, they were really denying Westmoreland and keeping air operations against the DRV under their control." To complicate matters, the U.S. ambassadors to Thailand (Graham Martin) and Laos (William H. Sullivan) exerted undue influence over operational and command arrangements.

This bizarre command structure went against the grain of the Air Force's single air manager concept, which dictated that one commander was to control and coordinate all aircraft within a combat theater. The chain through which operational strike requests had to flow gave some indication of the growing overcomplexity of the campaign. Requests for airstrikes originated with the 2nd Air Division and Task Force 77 in Vietnam and then proceeded to CINCPAC, who in turn reported to his superiors, the Joint Chiefs, at the Pentagon. After input from the State Department and the CIA, the requests then proceeded to the White House, where the president and his "Tuesday Cabinet" made decisions on the strike requests on a weekly basis.



Another problem exposed by Rolling Thunder was the unpreparedness of the Air Force for the operations it was undertaking. Its aircraft had been designed and its pilots trained for strategic operations against the Soviet Union – for nuclear, not conventional war. The new campaign exposed years of neglect in conventional tactics, while aircraft capabilities and armament were ill-suited to the task at hand. The Air Force was also embarrassed by the fact that the Navy was better prepared. It possessed the only all-weather fighter-bomber in the U.S. inventory in the new A-6 Intruder and was also responsible for the development of the F-4 Phantom fighter-bomber, which became ubiquitous during the Vietnam War.

Once air-to-air combat began over North Vietnam, the Air Force was again found lacking. The mainstay missiles of the air war turned out to be the Navy-developed AIM-9 Sidewinder and AIM-7 Sparrow, not its own AIM-4 Falcon. The Air Force continuously opposed adapting to the war in Southeast Asia, since its leadership believed that it was an aberration that would be quickly resolved. It could then turn its attention (and its more modern weapons) against the greater threat posed by the Soviet Union. None in the Air Force high command foresaw that the war would drag on for nearly a decade.

The Air Force did possess an aircraft which had an all-weather capability, radar-guided bombing equipment, and awesome destructive potential – the B-52 Stratofortress. The civilian administration, however, never considered utilizing the big bombers (whose operations remained under the control of the Strategic Air Command) very far north of the DMZ, believing that it was too overt an escalation. Air Force Chief of Staff John P. McConnell also opposed sending the bombers into the air defense environment in the north and limited B-52 strikes to Route Package One.

Compounding these issues was the one-year rotation policy adopted by the Pentagon in Southeast Asia. Although the first aircrews arriving in-theater were highly experienced, the rapidly growing tempo and ever-expanding length of the operation demanded more personnel. This exacerbated a growing lack of experienced aircrews. This dilemma was further compounded by an Air Force policy which dictated universal pilot training while proscribing involuntary second combat tours, which combined, had the effect of rotating personnel to different aircraft. Conversely, the Navy tended to maintain its aircrews within the same community for the duration of their careers, thereby retaining their expertise, but also incurring greater losses among experienced crews undergoing multiple combat tours.

Another factor was the weather within the operational theater. The cyclical monsoon patterns meant that the weather was deplorable for flight operations eight months of the year (from late September to early May) when rain and fog tended to conceal targets. Lack of adequate all-weather and night-bombing capability made it necessary for the majority of U.S. missions to be conducted during daylight hours, thereby easing the burden on the air defense forces of North Vietnam.

People's War in the air
Before Rolling Thunder even began the North Vietnamese leadership knew what was coming. It issued a February 1965 directive to the military and the population to "maintain communication and transportation and to expect the complete destruction of the entire country, including Hanoi and Haiphong." The communist leadership declared "a people's war against the air war of destruction...each citizen is a soldier, each village, street, and plant a fortress on the anti-American battlefront." All except those deemed "truly indispensable to the life of the capital" were evacuated to the countryside. By 1967, Hanoi's population had been reduced by half. Since gaining air superiority over U.S. forces was out of the question, the northern leadership decided to implement a policy of air deniability. At the beginning of the campaign, North Vietnam possessed approximately 1,500 anti-aircraft weapons, most of which were of the light 37 and 57mm variety. Within one year, however, the U.S. estimated that the number had grown to over 5,000 guns, including 85 and 100mm radar-directed weapons. That estimate was later revised downward from a high of 7,000 in early 1967 to less than a thousand by 1972. Regardless, during Rolling Thunder, 80 percent of U.S. aircraft losses were attributed to anti-aircraft fire.

Backing up the guns were the fighter aircraft of the North Vietnamese Air Force, which originally consisted of only 53 MiG-17 Fresco fighter aircraft. Though considered antiquated by the Americans when compared to their supersonic jets, the North Vietnamese turned their aircraft's weaknesses into strengths. They were fast enough for hit and run ambush operations and they were also maneuverable enough to shock the American fighter community by shooting down more advanced F-8 Crusaders and F-105 Thunderchiefs, which had to quickly develop new tactics. The newer missile-armed F-4 Phantom would become the American's primary dogfighting platform.

The simple appearance of MiGs could often accomplish their mission by causing American pilots to jettison their bomb loads as a defensive measure. In 1966, the MiG-17 were joined by more modern Soviet-built MiG-21 Fishbeds, which could fight on a more equal footing with the U.S. aircraft. By 1967, the North Vietnamese Air Force was maintaining an interceptor force of 100 aircraft, many of which were based on PRC airfields and out of reach of American air attack.

The northern economy was decentralized for its protection and large factories, located in the heavily populated Red River Delta region, were broken up and scattered into caves and small villages throughout the countryside. In the more heavily bombed southern panhandle, entire villages moved into underground tunnel complexes for the duration. Food shortages in North Vietnam became widespread, especially in the urban areas, as rice farmers went into the military or volunteered for service repairing bomb damage. When the nation's transportation system came under attack, destroyed bridges were repaired or replaced by dirt fords, ferries, and underwater and pontoon bridges. The system proved to be durable, well built, easily repaired, and practically impossible to shut down.

Perhaps North Vietnam's ultimate resource was its population. During 1965, 97,000 North Vietnamese volunteered to work full-time in repairing the damage inflicted by U.S. bombs. Another 370,000–500,000 worked part-time. When the nation's lines of communication came under attack, railroad supply trains and truck convoys were split into smaller elements which traveled only at night. The logistical effort was supported by citizens on sampans, driving carts, pushing wheelbarrows, or man-portering supplies on their backs to keep the war effort going. They were motivated by slogans like "Each kilogram of goods...is a bullet shot into the head of the American pirates."

SAMs and Wild Weasels
North Vietnam's deployment of SAMs forced American pilots to make hard choices: either approach targets at higher altitudes (to avoid anti-aircraft fire) and become prey to SAMs, or fly lower to avoid the missiles and become the target of anti-aircraft batteries. Due to altered tactics and the increased use of electronic radar jamming, the record of SAM kills decreased over time. The already dismal missile success rate fell from one kill for 30 launches to less than one kill for 50. Those figures do, however, say a great deal about the inefficiency of Rolling Thunder, since North Vietnam's SAM batteries never lacked sufficient stocks of missiles, regardless of efforts to interdict the supply system.



The nature of the gradual escalation had given Hanoi time to adapt to the situation. By 1967, North Vietnam had formed an estimated 25 SAM battalions (with six missile launchers each) which rotated among approximately 150 sites. With the assistance of the Soviet Union, the North Vietnamese had also quickly integrated an early warning radar system of more than 200 facilities which covered the entire country, tracking incoming U.S. raids, and then coordinating SAMs, anti-aircraft batteries, and MiGs to attack them. During 1967 U.S. losses totaled 248 aircraft (145 Air Force, 102 Navy, and one Marine Corps).

To survive in this ever more lethal air defense zone, the U.S. had to adopt newer, more specialized tactics. Large-scale strikes, known as force packages in the Air Force and multi-carrier "Alpha strikes" by the Navy, were assigned numerous support aircraft to protect the fighter-bombers. First into the target areas were specialized Iron Hand flak suppression missions. These consisted of F-105 Wild Weasel hunter/killer teams configured with sophisticated electronic equipment to detect and locate the emissions associated with SAM guidance and control radars.

The Wild Weasels also carried electronic countermeasures (ECM) equipment to protect themselves. They directed flak suppression strikes and carried AGM-45 Shrike anti-radiation missiles (another Navy development), which homed in on the radar systems of the SAMs. The SA-2 had greater range than the Shrike, but if the Shrike was launched and the radar operator stayed on the air, the American missile would home in on the signal and destroy the radar source. A sophisticated cat and mouse game then ensued between North Vietnamese radar operators and the Wild Weasel pilots. The Navy also utilized aircraft in a similar role, but did not create a specialized unit like the Wild Weasels to conduct SAM suppression.



Next came the bomb-laden strike aircraft protected by escort fighters (Combat Air Patrol or MIGCAP) and electronic jamming aircraft to degrade enemy radar. New ECM devices had hurriedly been deployed to protect aircraft from missile attacks, but they remained subject to frequent breakdowns because of climate conditions in Southeast Asia. Also included in the missions were KC-135 aerial tankers and Search and Rescue (SAR) helicopters, which were, in turn, protected by propeller-driven A-1 escorts.

From mid-1966 until the end of 1967, President Johnson continued to dole out sensitive targets one by one to the generals while simultaneously trying to placate the doves in Congress and within his own administration with periodic cutbacks and half-hearted peace initiatives. In the end, this erratic course satisfied no one and did little to alter the course of the war.

The nature of the targets and the risks involved in striking (and re-striking) them began to take a toll. Chief of Naval Operations David McDonald reported to his co-chiefs after a trip to South Vietnam in September 1966, that Rolling Thunder aircrews were angered with the targeting process and that they faulted the campaign due to "guidelines requiring repetitive air programs that seemed more than anything else to benefit enemy gunners." During 1967, the second full year of Rolling Thunder operations, 362 U.S. aircraft had been lost over North Vietnam. (208 Air Force, 142 Navy, and 12 Marine Corps).

MiGs and interdiction
Rolling Thunder reached the last stage of its operational evolution during 1967 and 1968. The chief purpose of the American air effort in the higher Route Packages of North Vietnam was slowly transformed into that of interdicting the flow of supplies and materiel and the destruction of those segments of the north's infrastructure that supported its military effort. Although most U.S. aircraft losses continued to be inflicted by anti-aircraft fire, U.S. Air Force F-105s and Navy A-4 Skyhawks increasingly encountered SAMs and MiGs. North Vietnamese fighters also became a particular problem because of the lack of radar coverage in the Red River Delta region, which allowed the MiGs to surprise the strike forces. Airborne early warning aircraft had difficulty detecting the fighters at low altitudes and the aircraft themselves were difficult to see visually.



While F-105s did score 27 air-to-air victories, the overall exchange ratio was near parity. In January 1967, the Americans sprang a surprise on the MiGs when they launched Operation Bolo. F-4 Phantoms, using the same radio call signs, direction of approach, altitude, and speed as a typical flight of bomb-laden F-105s, lured the MiGs toward what the MiG pilots thought would be easy prey. The result was seven MiGs shot down within 12 minutes.

Later in the year, the U.S. launched its most intense and sustained attempt to force North Vietnam into peace negotiations. Almost all of the targets on the Joint Chiefs' list had been authorized for attack, including airfields that had been previously off limits. Only central Hanoi, Haiphong, and the PRC border area remained prohibited from attack. A major effort was made to isolate the urban areas by downing bridges and attacking LOCs. Also struck were the Thai Nguyen steel complex (origin of the Pardo's Push), thermal and electrical power plants, ship and rail repair facilities, and warehouses. North Vietnamese MiGs entered the battle en masse, as their capital was threatened and kill ratios fell to one U.S. aircraft lost for every two MiGs. During 1968, MiGs accounted for 22 percent of the 184 American aircraft (75 Air Force, 59 Navy, and five Marine Corps) lost over the north. As a result, operations against the last of North Vietnam's airfields, previously off-limits to attack, were authorized.

Despite the best interdiction efforts of Rolling Thunder, however, the NLF and PAVN launched their largest offensive thus far in the war on 30 January 1968, striking throughout South Vietnam during the lunar new year holiday. The Tet Offensive concluded as a military disaster for North Vietnam and its NLF allies, but it also adversely affected U.S. public opinion, which in turn affected the will of Washington. Fortunately for North Vietnam, many U.S. bombing advocates (including Air Force Chief of Staff McConnell) did not want to risk the one aircraft capable of delivering a lot of bombs in bad weather – the B-52. Without them, there was little that could be done over the north in response to Tet, since bad weather minimized fighter operations until the beginning of April.

Opposition
Writing after the war, Robert McNamara stated that by spring 1967 he and other civilians in the administration had become convinced that both Rolling Thunder and the ground war in South Vietnam were not working. McNamara claimed that he and others within the administration continuously opposed the Joint Chief's recommendations for an increased tempo of bombing and the loosening of target restrictions. The generals found themselves on the horns of a dilemma of their own making. They continuously claimed that the campaign was working, yet they also had to continuously demand greater latitude in order to make the campaign succeed. The limited goals entailed in American foreign policy and the military's goal of total victory were simply not reconcilable. The great conundrum had then become how to defeat North Vietnam without defeating North Vietnam.

On 9 August 1967 the Senate Armed Services Committee opened hearings on the bombing campaign. Complaints from the armed services had sparked the interest of some of the most vocal hawks on Capitol Hill. The military chiefs testified before the committee, complaining about the gradual nature of the air war and its civilian-imposed restrictions. It was obvious that McNamara, the only civilian subpoenaed and the last to testify before the committee, was to be the scapegoat. The Secretary of Defense marshaled his objections to an indiscriminate air war and adeptly rebutted the charges of the military chiefs. He bluntly admitted that there was "no basis to believe that any bombing campaign...would by itself force Ho Chi Minh's regime into submission, short, that is, of the virtual annihilation of North Vietnam and its people."

It had now become clear to President Johnson that McNamara had become a liability to the administration. In February 1968, McNamara resigned his position and was replaced by Clark Clifford, who was chosen because of his personal friendship with Johnson and his previous opposition to McNamara's suggestions that the number of troops in the South Vietnam be stabilized and that Rolling Thunder be ended. McNamara's position, however was almost immediately taken up by Secretary of State Dean Rusk, (until then an ardent advocate of the bombing campaign). Rusk proposed limiting the campaign to the panhandle of North Vietnam without preconditions and awaiting Hanoi's reaction. Within months Clifford too began to adopt the views of the man he had replaced, gradually becoming convinced that the U.S. had to withdraw from an open-ended commitment to the war.

Disappointed by perceived political defeats at home and hoping that Hanoi would enter into negotiations, President Johnson announced on 31 March 1968, that all bombing north of the 19th parallel would cease. As a result of that decision, into the area between the 17th and 19th parallels, the Air Force and Navy began to pour all the firepower that they had formerly spread throughout North Vietnam. The Air Force doubled the number of sorties sent into Route Package One to more than 6,000 per month with the campaign concentrated on interdiction "choke points", road closing, and truck hunting. Once again, the military commanders were faced a familiar dilemma: having opposed the bombing cutback, they then decided that the new policy had a lot of merit, especially when considering the alternative of no bombing at all. The North Vietnamese responded by doubling the number of anti-aircraft batteries in the panhandle, but most of their SAM batteries remained deployed around Hanoi and Haiphong.

Hanoi, which had continuously stipulated that it would not conduct negotiations while the bombing continued, finally agreed to meet with the Americans for preliminary talks in Paris. As a result, President Johnson declared that a complete bombing halt over North Vietnam would go into effect on 1 November 1968, just prior to the U.S. presidential election. Although the bombing halt was to be linked to progress in the peace talks, the Joint Chiefs were skeptical that the administration would reopen the bombing campaign under any circumstances. They were correct.

Conclusions
Between March 1965 and November 1968, aircraft of the U.S. Air Force had flown 153,784 attack sorties against North Vietnam, while the Navy and Marine Corps had added another 152,399. On 31 December 1967, the Department of Defense announced that 864,000 tons of American bombs had been dropped on North Vietnam during Rolling Thunder, compared with 653,000 tons dropped during the entire Korean War and 503,000 tons in the Pacific theater during the Second World War.

The CIA estimated on 1 January 1968 that damage inflicted in the north totaled $370 million in physical destruction, including $164 million worth of damage to capital assets (such as factories, bridges, and power plants). The agency also estimated that approximately 1,000 casualties had been inflicted on the North Vietnamese population per week, or approximately 90,000 for the 44-month period, 72,000 of whom were civilians.

Due to combat and operational circumstances, 506 U.S. Air Force, 397 Navy, and 19 Marine Corps aircraft were lost over or near North Vietnam. During the operation, of the 745 crewmen shot down, the U.S. Air Force recorded 145 rescued, 255 killed, 222 captured (23 of whom died in captivity), and 123 missing. Figures on U.S. Navy and Marine Corps casualties were harder to come by. During the 44-month time frame, 454 Naval aviators were killed, captured, or missing during combined operations over North Vietnam and Laos.

Rolling Thunder had begun as a campaign of psychological and strategic persuasion, but it changed very quickly to interdiction, a tactical mission. Its ultimate failure had two sources, both of which lay with the civilian and military policy-makers in Washington: First, neither group could ever conceive that the North Vietnamese would endure under the punishment that they would unleash upon it. The civilians, moreover, did not understand air power well enough to know that their policies might be crippling it; Second, the American military leadership failed to initially propose and develop, or later to adapt, an appropriate strategy for the war.

Along the way, Rolling Thunder also fell prey to the same dysfunctional managerial attitude as did the rest of the American military effort in Southeast Asia. The process of the campaign became an end unto itself, with sortie generation as the standard by which progress was measured. Sortie rates and the number of bombs dropped, however, equaled efficiency, not effectiveness. There is an argument that it wasn't even efficient since in order to increase the sortie rate sometimes eight planes were sent with small bomb loads when one or two planes could have carried out the same mission.

Legacy
The U.S fighter community was shocked by the news that elderly subsonic fighters were inflicting losses against the F-105 Thunderchief, the fastest and most sophisticated strike fighter then in the Air Force inventory. One result was a drastic rethinking of air combat and aircraft design, which had been centered around delivery of nuclear weapons in Europe and missile interception. As a result, the F-4 Phantom became the primary U.S. air superiority fighter for both services in the later days of the war. The Air Force's F-4E was fitted with maneuvering slats and an internal gun, while the Navy cancelled an expensive new fighter design in favor of a plane that would be more, rather than less effective, in a short-range dogfight than the Phantom. Analysis of the campaign resulted in the creation of new pilot training programs, such as the famous TOPGUN, utilizing F-5 Tigers and A-4 Skyhawks to simulate the threat of small subsonic and supersonic MiG fighters. The U.S. also started the design of a new generation of fighters that were optimized for visual-range dogfights. Although the first of these "teen" fighters would not enter service soon enough to cover America's withdrawal from Vietnam, they would dominate future air battles, serving well into the 21st century. Many remain in service today.

Published government documents

 * Berger, Carl, ed, The United States Air Force in Southeast Asia, 1961–1973. Washington DC: Office of Air Force History, 1977.
 * Corum, Col. Delbert, et al and Maj. Paul Burbage, et al, The Tale of Two Bridges and The Battle for the Skies over North Vietnam, 1964–1972. Maxwell Air Force Base AL: Air University Press, 1976.
 * Department of State, Aggression from the North: The Record of North Vietnam's Campaign to Conquer South Vietnam. Washington DC: U.S. Government Printing Office, 1965.
 * Head, William P. War Above the Clouds: B-52 Operations During the Second Indochina War and the Effects of the Air War on Theory and Doctrine. Maxwell Air Force Base AL: Air University Press, 2002.
 * Marolda, Edward J. By Sea, Air, and Land: An Illustrated History of the U.S. Navy and the War in Southeast Asia. Washington DC: Naval Historical Center, 1994.
 * Schlight, Col. John, A War Too Long: The USAF in Southeast Asia, 1961–1975. Washington DC: Air Force History and Museums Program, 1996.
 * Schlight, Col. John, The War in South Vietnam: The Years of the Offensive, 1965–1968. Washington DC: Air Force History and Museums Program, 1999.
 * Spector, Ronald H. The United States Army in Vietnam: Advice and Support, 1941–1960. Washington DC: United States Army Center of Military History, 1983.
 * Thompson, Wayne, To Hanoi and Back: The U.S. Air Force and North Vietnam, 1966–1973. Smithsonian Institution Press, 2002.
 * Tilford, Earl H. Setup: What the Air Force Did in Vietnam and Why. Maxwell AFB AL: Air University Press, 1991.
 * Van Staaveren, Jacob, Gradual Failure: The Air War Over North Vietnam, 1965–1966. Washington DC: Air Force History and Museums Program, 2002.
 * Declassified CIA documents concerning Operation Rolling Thunder

Document collections

 * Gravel, Senator Mike, ed., The Pentagon Papers: The Defense Department History of United States Decisionmaking on Vietnam 5 vols. Boston: Beacon Press, 1971.
 * Sheehan, Neil, Hedrick Smith, E.W. Kenworthy, & Fox Butterfield, The Pentagon Papers as Published by the New York Times. New York: Ballentine, 1971.

Biographies & memoirs

 * McNamara, Robert S. with Brian VanDeMark, In Retrospect: The Tragedy and Lessons of Vietnam. New York: Times Books, 1995.
 * Johnson, Lyndon B. The Vantage Point: Perspective on the Presidency, 1963–1969. New York: Holt, Rhinehart, and Winston, 1971.