Air War: Operation Rolling Thunder

Through the American strategic bombing campaign over North Vietnam, the essence of the frustration met by the United States in Vietnam can be discovered. The bombing of North Vietnam escalated in parallel with the buildup of U.S. ground forces in South Vietnam. The initial goal was cessation of Hanoi's support for the National Liberation Front insurgency in the south, in order to prevent a need for massive deployment of U.S. ground troops.

In 1964, the U.S. Joint Chiefs of Staff believed that North Vietnam, a small nation with an industrial base only beginning to recover from its war with the French, would be reluctant to risk its own economic stability for the sake of the insurgency in the south. Civilian leaders in the Johnson Administration agreed with this assessment, although geopolitical concerns led them to disagree over the scope of the air campaign.

The military men advocated a course of action calculated to destroy North Vietnamese will and capacity to continue its support for the insurgency in the south. A list of targets including bridges, railway yards, shipping docks, army barracks and supply depots was drawn up. President Johnson withheld approval. He and his civilian contemporaries feared that an air campaign over North Vietnam could set off a nuclear confrontation with the Soviet Union, or possibly cause the Chinese to send tens of thousands of troops across the border, as they had done in 1950 in Korea.

Initially, U.S. Air Force attacks were mounted from bases in South Vietnam. Over the course of Operation Rolling Thunder, four air bases in Thailand served as launch points for the majority of USAF activity. Aircraft refueled over Laos before continuing on to their targets in North Vietnam. U.S. Navy airstrikes were launched from aircraft carriers cruising off North Vietnam, with the majority of their targets situated in coastal regions.

Operation Rolling Thunder map
On U.S. maps, Hanoi and Haiphong were marked by concentric disks. The red, outer disk represented a restricted zone, requiring permission from Washington. The yellow, inner disk represented a zone that was prohibited in all circumstances.
The buffer zone marked by diagonal red stripes was established to prevent violations of Chinese airspace.

Rolling Thunder Gradually Evolves

In February 1965 a plan for an eight-week air campaign was adopted, with the code name Rolling Thunder. Initially the bombing was limited to targets below the 19th parallel, north of the Vietnamese Demilitarized Zone but far south of the Chinese border. Missions were severely limited by a requirement for approval from Washington for every target, on the timing of every attack and for the types of aircraft and ordnance to be used. The bombing campaign was rolled out in accordance with a doctrine of "gradualism", designed to ensure that China would have an opportunity to warn the Americans if a limit to their tolerance was being approached.

Geographical restrictions were incrementally relaxed, although throughout 1965 greater Hanoi and the area surrounding the port city of Haiphong remained off-limits. A thirty-mile buffer zone along the Chinese frontier was also proscribed. These regions contained the majority of North Vietnamese facilities possessing militarily strategic value.

In April, President Johnson and Secretary of Defense Robert McNamara, were persuaded to begin to attack North Vietnamese lines of supply, marking a shift from targets of psychological significance to targets of strategic military importance. Bridges and ferries were destroyed, to degrade North Vietnamese ability to distribute supplies received from China and the Soviet Union. Other targets included radar installations, military barracks and ammunition depots.

Why Operation Rolling Thunder Failed

Since the inception of the operation, American military leaders had advocated targeting the North's petroleum, oil and lubricant storage areas in order to cause the North's military effort to literally grind to a halt. In June 1965, they were given the go-ahead and first indications were that the effort would achieve its objective. The CIA produced an estimate that 70% of North Vietnam's oil facilities had been destroyed. This proved to be only a short-term inconvenience, as Hanoi had dispersed the majority of its reserves across the country in 50-gallon drums. The resilience and endurance of the Vietnamese was proving to be their ultimate resource.

On the ground, large factories in heavily populated regions were split up and scattered into caves and small villages throughout the countryside. In the heavily bombed region just north of the Demilitarized Zone, entire villages were moved into underground tunnel complexes. When North Vietnamese transportation infrastructure became the focus of bombing raids, destroyed bridges were repaired or were substituted for with dirt fords, cross-stream ferries, and pontoon or sub-surface bridges. When overland supply routes came under attack, freight trains and truck convoys were split into smaller units which only moved at night.

In Code Warriors, Stephen Budiansky states that captured North Vietnamese signals intelligence documents revealed that plain-language U.S. Air Force voice transmissions provided a major source of advance warnings. In 80 to 90 percent of Rolling Thunder missions, the North Vietnamese were aware of the impending attack at least 30 to 45 minutes in advance.

War in the Skies of North Vietnam

With U.S. air superiority an indisputable fact, the North Vietnamese, with support from their Soviet and Chinese backers, began a steep build-up of anti-aircraft weapons. Over the course of the entire operation, 80% of U.S. aircraft losses were attributed to anti-aircraft guns, which included 85 and 100 mm radar-directed weapons. By the end of Rolling Thunder, the Democratic Republic of Vietnam had 7,500 antiaircraft guns and two hundred Soviet-made SA-2 Guideline surface-to-air missile sites.

The North Vietnamese Air Force had in February 1964 received 36 MiG-17 fighter aircraft as a "gift" from the Soviet Union. Mig-17s were subsonic and gun-armed — compared to U.S. supersonic jet fighters they seemed antiquated. In 1966, the Vietnam People's Air Force acquired supersonic, missile-armed MiG-21s from the Soviets, dramatically increasing the threat to U.S. aircraft. By 1967 the VPAF possessed an interceptor force of 100 aircraft. Many of those were based in Chinese airfields, putting those aircraft strictly off-limits to American aircraft.

USAF fighter pilots had superior aircraft and training, but the MiG pilots had a few home-field advantages. These included guidance from ground controllers using early warning radar and an option to wait for ideal circumstances. American aircraft were only attacked when they were laden with bombs, were low on fuel, or had been damaged. The MiGs were small and hard-to-see. Typically they only made one pass, at a high speed, then fled for the sanctuary of their own airfields, which were not bombed until mid-1967, or escaped across the border to China. Since they were always over friendly territory, damaged MiGs could be repaired and returned to action quickly.

The Impact of Operation Rolling Thunder

As the bombing campaign approached its final stage during 1967 and 1968, its chief purpose had slowly transformed from psychological and strategic persuasion to the interdiction of supply and material flows in North Vietnam and the destruction of military infrastructure. Despite the bombing campaign, on January 30, 1968 the People's Army of Vietnam and the Viet Cong launched the Tet Offensive; their largest offensive in the war thus far.

As 1968 drew to a close, Hanoi finally agreed to meet for preliminary discussions. In response, President Johnson declared that a complete bombing halt would go into effect on November 1, just prior to the presidential election. Three and a half years would pass before North Vietnam again became the target of intensive U.S. bombing.