The Air War: Rolling Thunder, the Trail, the B-52s and Linebacker

A U.S. Air Force B-52D Stratofortress drops a string of bombs over Vietnam. The first B-52 “Arc Light” strike in the war was flown on 18 June 1965; the last great B-52 campaign, Linebacker II, came in December 1972. Photo: U.S. Air Force, public domain via Wikimedia Commons.

The Vietnam War · Chapter 5 of 9

The Air War

Between 1964 and 1973 the United States dropped more than twice the tonnage of bombs that all the Allies dropped in the Second World War, on North and South Vietnam, Laos and Cambodia, in a war in which air power was used with great restraint and great violence at the same time.

1964 – 1973Hanoi · Haiphong · the Ho Chi Minh Trail · Yankee Station · Guam · Thailand~27 min read

The Vietnam War was fought on the ground in South Vietnam, but it was fought above all of Indochina. American aircraft bombed North Vietnam for nearly four years under Operation Rolling Thunder and again in 1972 under Linebacker I and II; they bombed the Ho Chi Minh Trail through Laos and Cambodia almost continuously from 1965 to 1973; B-52s dropped their loads in “Arc Light” strikes on suspected enemy positions in the South; helicopters carried the Army into battle and brought its wounded out; fixed-wing transports and gunships flew day and night; and Air Force C-123s sprayed millions of gallons of herbicide over the South Vietnamese countryside. All US bombing in Southeast Asia from 1964 to 1973 came to more than seven million tons, more than twice what all the Allies dropped in the Second World War.

This chapter tells that story and the arguments about it. The bombing of North Vietnam was the most closely controlled air campaign the United States has ever fought, directed in its targets and timing from the White House, and it is still argued over: whether it was too restrained to succeed, or could not have succeeded against a pre-industrial country supplied by China and the Soviet Union whatever the restraints; whether the B-52s of December 1972 brought Hanoi back to the table, or merely bought the agreement that had already been reached. The human cost fell on the aircrews, more than a thousand of them killed or captured over the North, and on the people below, among them tens of thousands of North Vietnamese civilians and the people of Laos, where unexploded bombs still kill and maim.

A note on evidence. The statistics here come from official compilations: the Naval History and Heritage Command and the Air Force Historical Support Division, the National Museum of the US Air Force, the Vietnam Helicopter Pilots Association’s loss database, the Institute of Medicine’s review of the herbicide program, and congressional testimony on Laos. Where figures from different sources disagree, the box near the end of the chapter says so.

Rolling Thunder: Bombing the North, 1965–1968

Operation Rolling Thunder began on 2 March 1965, when more than a hundred Air Force and South Vietnamese aircraft struck an ammunition depot at Xóm Bàng in the southern part of North Vietnam; Lt. Col. Robinson Risner led the American strike. It was meant, in the thinking of Johnson’s civilian advisers, as graduated pressure: a slowly rising campaign that would show Hanoi the cost of continuing the war in the South and give it reasons to negotiate, while never threatening the North’s survival or provoking China or the Soviet Union into intervening as China had in Korea. Its military purposes were to reduce infiltration and to raise South Vietnamese morale.

The Naval History and Heritage Command divides the campaign into five phases. Until mid-1965 it struck military targets in the southern part of the North. From July 1965 to January 1966 it attacked the transport system: roads, bridges, boats and railways. In 1966 it went after petroleum storage, and from October 1966 to May 1967 after industry and power plants, including the first strikes on Hanoi. From May 1967 to October 1968 it hit the remaining industrial targets and targets of opportunity. It was suspended several times for diplomatic initiatives, the longest pause lasting 37 days over the new year of 1965–66. On 31 March 1968, after Tet, Johnson limited the bombing to the area south of the 19th parallel (Chapter 6), and on 31 October 1968 he announced its end, effective the next day.

The figures are very large. Air Force and Navy aircraft flew more than 300,000 combat sorties over the North, the Navy and Marines 152,399 attack sorties and the Air Force 153,784, and dropped 864,000 tons of bombs and missiles. The NHHC compares that with the 653,000 tons of conventional bombs dropped in the three years of the Korean War and the 503,000 tons dropped in the Pacific theatre in the Second World War. North Vietnam shot down 922 American aircraft in the campaign.

The North Under the Bombs

North Vietnam adapted to the bombing rather than giving way to it. From 1965 Hanoi evacuated much of its population, and most of its children, to the countryside; factories were broken up and moved to villages and caves; individual concrete shelters were sunk along the city’s streets. When the Americans struck the North’s fuel storage in the summer of 1966, destroying most of the large tank farms, the fuel had already been dispersed into drums hidden along roads and in villages. Destroyed bridges were replaced by fords, ferries and pontoon bridges that could be hidden by day. Hundreds of thousands of civilians, many of them in youth brigades, were organized to repair roads and railways within hours of a strike.

The North did not do this alone. China sent large numbers of engineering, railway and anti-aircraft troops to North Vietnam from 1965 to 1968, freeing Vietnamese soldiers for the South; Chinese scholarship based on Chinese archives, notably that of Chen Jian, puts the total at about 320,000 over those years. The Soviet Union supplied the SA-2 missiles, the MiG-21s, radars and much of the heavy equipment, with Soviet technicians to train the crews. The American policy of limiting the war so as not to bring China in, which shaped every restriction described below, was built on a real danger; the Chinese presence was larger than Washington knew at the time.

Civilians died in the bombing, in numbers that are hard to establish. Estimates of North Vietnamese civilians killed by American bombing in the whole war, compiled from several sources, are of the order of 65,000; Hanoi has published only aggregate figures for the war as a whole. American policy forbade attacks on population as such, and the restrictions on targets around Hanoi and Haiphong were partly meant to limit civilian deaths; but bombs aimed at bridges, rail yards and depots in towns killed the people who lived around them, and the North’s government made the most of every such death in its propaganda and in its welcome to visiting Western journalists and activists.

Route Packages, Restrictions and the Tuesday Lunch

From 1966 North Vietnam was divided into six “route packages” to share out the targets between the services. The Navy took the coastal packages, II, III, IV and VI-B, around Haiphong; the Air Force took V and VI-A, and Route Package I, just north of the DMZ, came under MACV, which included Hanoi and the railways to China. Route Package VI, the Red River delta around the two cities, was among the most heavily defended places on earth.

What made Rolling Thunder unique was the degree of political control. Targets were chosen in Washington, many of them at the President’s Tuesday lunch with McNamara, Secretary of State Dean Rusk and the national security adviser, and sent down the chain of command with instructions on the number of sorties and even the timing. For much of the campaign there were zones around Hanoi and Haiphong where pilots could not strike without specific approval, a buffer along the Chinese border, and, for the first two years, a ban on attacking the MiG bases. The SAM sites were at first off limits while under construction. Pilots and commanders deeply resented the restrictions, and many later argued that they had been sent to fight with one hand tied. Johnson and his advisers saw them as the price of keeping the war limited, with Korea’s experience of Chinese intervention in mind.

Historians remain divided. Mark Clodfelter’s The Limits of Air Power (1989) argues that the restrictions were not the main problem: that a guerrilla and conventional war in the South, fought by an enemy who needed only a few dozen tons of supplies a day from the North and received its arms from China and the Soviet Union, could not be stopped by bombing an agricultural country, however intensively. Others, including many of the air commanders, argue that a sharp, unrestricted campaign against Hanoi and Haiphong in 1965 would have had a different result, and point to Linebacker in 1972. A third view, argued by Daniel Isaacs and others, is that the “one hand tied” image is itself misleading, given the tonnage actually dropped.

Thuds, Phantoms and the Thai Bases

The Air Force flew most of its strikes on the North from bases in Thailand, which the Thai government allowed on the understanding that their role would not be publicized: Korat, Takhli, Udorn, Ubon and Nakhon Phanom, with U-Tapao on the Gulf of Thailand for B-52s and tankers from 1967. The workhorse of the early years was the Republic F-105 Thunderchief, the “Thud”, a single-seat fighter-bomber designed to carry a nuclear weapon at low level, which flew more strikes over the North than any other type and suffered the heaviest losses. Strike packages of F-105s refuelled from KC-135 tankers over Laos on the way in. The McDonnell F-4 Phantom II, flown by both the Navy and the Air Force, took over more and more of the strike and escort role from 1966–67.

North Carolina’s main contribution to the air war came from Goldsboro. Seymour Johnson Air Force Base, home of the 4th Tactical Fighter Wing, had flown the F-105 since 1958; the Phantom arrived in 1967, and from 1972 the wing’s tactical squadrons rotated to Ubon Royal Thai Air Force Base for combat operations until the end of the war. The base also housed a Strategic Air Command bomber wing, the 68th, from 1958 to 1982, and at the war’s end it was one of the bases to which returning prisoners of war were brought home. At Havelock, Marine Corps Air Station Cherry Point sent three A-6 Intruder squadrons to the Far East and trained aircrew and replacements for the Marine air war.

SAMs, MiGs and the Wild Weasels

North Vietnam built, with Soviet and Chinese help, the densest air defence system the world had yet seen: thousands of anti-aircraft guns, from rifle-calibre weapons to radar-directed 100 mm guns; Soviet-built SA-2 surface-to-air missiles; and MiG-17, MiG-19 and MiG-21 fighters under ground control. Guns caused most American losses; the SA-2, which brought down its first American aircraft, an Air Force F-4C, on 24 July 1965, forced strike aircraft down into the gunfire. The MiGs shot down fewer aircraft than either, but by forcing fighter-bombers to jettison their bombs or to carry escorts they reduced every strike.

The Americans answered with electronic warfare and with the Wild Weasels: two-seat aircraft, first F-100Fs and then F-105Fs and F-105Gs, whose crews carried receivers that could find the Fan Song radars of the SA-2 sites and attacked them with Shrike anti-radiation missiles and bombs. The Weasels flew first into the defended area and left last; the signature defensive manoeuvre against an SA-2 was the “SAM break”, a hard diving turn timed to make the missile overshoot. Against the MiGs the Air Force’s most famous success was Operation Bolo on 2 January 1967, planned by Col. Robin Olds of the 8th Tactical Fighter Wing at Ubon: F-4s flying the call signs and routes of bomb-laden F-105s lured the MiG-21s up and shot down seven of them in about twelve minutes without loss.

The cost to the aircrews was heavy. The Defense Department reported on 9 January 1967 that 599 fixed-wing aircraft of all services and 255 helicopters had been lost in the war to that date. The Navy lost 600 aviators and the Marine Corps 271 in the whole war; 170 naval aviators and aircrew were captured, and 160 came home in 1973. Most of the men held in the Hỏa Lò prison (“the Hanoi Hilton”) and the other camps around Hanoi, among them Jim Stockdale, Jeremiah Denton and John McCain, were shot down during Rolling Thunder; so was Robinson Risner, who had led its first mission and was captured in September 1965. Their story is told in Chapter 8 and on the page The Hanoi Hilton.

The Navy on Yankee Station

The Navy fought its air war from the carriers of Task Force 77 in the Gulf of Tonkin, at a point off the North Vietnamese coast called Yankee Station, and, until 1966, at Dixie Station off the South. Usually three carriers were on line, launching “Alpha strikes” of dozens of A-4 Skyhawks, A-6 Intruders, F-4 and F-8 fighters and supporting aircraft against the bridges, ports and power plants of Route Package VI, or flying close air support in the South. The NHHC records that Navy fighters shot down 29 enemy aircraft in Rolling Thunder for the loss of eight Navy aircraft to MiGs. The deadliest day for the carrier force was not in combat: on 29 July 1967 a Zuni rocket fired accidentally on the flight deck of USS Forrestal set off fires and bomb explosions that killed 134 men. Lt. Cdr. John McCain was in one of the aircraft on deck and escaped; he was shot down from USS Oriskany three months later.

The Ho Chi Minh Trail and the War in Laos

The supply line that Rolling Thunder was meant to choke ran mostly through a neutral country. The Ho Chi Minh Trail (to the Vietnamese, the Trường Sơn road) left North Vietnam through the mountain passes of Mụ Giạ and Ban Karai, ran south through the Laotian panhandle past Tchepone, and fed into South Vietnam and Cambodia through dozens of branches. Begun as footpaths by Group 559 in 1959, by the late 1960s it was a network of thousands of kilometres of truck roads, bypasses, fuel pipelines, depots and anti-aircraft defences, worked by tens of thousands of soldiers, engineers and volunteers, many of them young women.

The United States bombed it from 1965 to 1973 in a series of campaigns, Steel Tiger, Tiger Hound and, from late 1968, the Commando Hunt series, that were officially secret because Laos was neutral under the Geneva agreement of 1962. To find trucks moving at night under the jungle canopy, the Igloo White program from 1968 seeded the Trail with acoustic and seismic sensors, many dropped by aircraft, that relayed signals to orbiting aircraft and to a computer centre, Task Force Alpha, at Nakhon Phanom in Thailand. Gunships and fighter-bombers were directed onto the targets. Air Force claims of trucks destroyed ran into the tens of thousands, but post-war analysis cast doubt on them, and the flow of men and supplies down the Trail was never stopped.

The bombing of Laos was on a scale that few Americans knew about at the time. Congressional testimony in 2010 put the total at more than two million tons dropped in some 580,000 bombing runs between 1964 and 1973, making Laos, per head of population, among the most heavily bombed countries in history. Much of it was cluster munitions, and up to 30 percent of the submunitions failed to explode. Since the war, at least 20,000 people in Laos have been killed or injured by unexploded ordnance, and clearance continues, with American funding, more than fifty years later.

Arc Light: the B-52s in the South

The first B-52 strike of the war, on 18 June 1965, sent 27 bombers from Guam against a suspected Viet Cong base north of Saigon; two collided over the Pacific on the way and eight crewmen died, and the results on the ground were meagre. But the “Arc Light” strikes, as they were called, became a fixture of the war. Flying from Andersen Air Force Base on Guam, from Kadena on Okinawa and, from 1967, from U-Tapao in Thailand, cells of three B-52s bombed from about 30,000 feet, unseen and unheard until the bombs landed. A “Big Belly” B-52D could carry 108 bombs. The strikes were used against base areas, troop concentrations and the Trail, and in direct support of troops: at Ia Đrăng in November 1965 (Chapter 4) and, on the largest scale, around Khe Sanh in 1968, where Operation Niagara dropped 98,721 tons of bombs in support of the besieged Marines (Chapter 6). Many captured PAVN and Viet Cong soldiers described the strikes as the thing they feared most. From March 1969 B-52s also bombed Cambodia in secret, the Menu operations, a subject of Chapter 8.

The Helicopter War

If the B-52 was the war’s heaviest weapon, the helicopter was its symbol. The Bell UH-1 Iroquois, the “Huey”, carried the infantry into combat assaults, resupplied them, flew gunship escort with rockets and machine guns, and evacuated the wounded; in its many versions it was the most numerous aircraft of the war. The tandem-rotor CH-47 Chinook lifted artillery, ammunition and fuel to fire bases; the giant CH-54 Tarhe (“Flying Crane”) recovered downed aircraft; the Marines flew the UH-34 and CH-46; the small OH-6 “Loach” flew scouting missions at treetop height, where it was often shot down. In 1967 the AH-1G Cobra, the first purpose-built attack helicopter, entered combat. The Air Force flew HH-3 and HH-53 “Jolly Green Giant” rescue helicopters into North Vietnam and Laos to pick up downed aircrew, with A-1 Skyraiders, the propeller-driven “Sandys”, covering them. Rescue was a matter of honour: crews went in under fire for downed airmen time after time, and some of the war’s costliest rescue efforts, such as the eleven-day attempt in April 1972 to recover Lt. Col. Iceal Hambleton, call sign Bat 21, near the DMZ, cost more lives than they saved. Behind the combat aircraft stood the airlift: Air Force C-130s, C-123s and C-7 Caribous, flying into short dirt strips across South Vietnam, carried the troops, ammunition and food that kept the bases supplied, and at Khe Sanh in 1968 kept a besieged base alive (Chapter 6).

The losses were correspondingly large. The Vietnam Helicopter Pilots Association, whose database of tail numbers is the most complete record, counts 5,607 helicopters lost in the war out of about 11,800 for which it has records, and 2,165 pilots and 2,712 other crewmen killed. An older and frequently cited Defense Department figure of about 5,086 helicopters destroyed is lower because it counts differently; the VHPA includes all losses, from accidents as well as enemy action.

Gunships and the Close Air War

Much of the air war was flown over South Vietnam in support of troops on the ground. Air Force F-100s, F-4s and A-37s, Navy and Marine A-4s, and the old propeller-driven A-1 Skyraider, which could carry a heavy load and stay over a fight for hours, flew close air support under the direction of forward air controllers in light O-1 and O-2 spotter planes. Many Americans and South Vietnamese owed their lives to an air strike called in at the right moment; many villages were destroyed by strikes called in on fire from them.

The gunship was a new idea. A Second World War transport, the C-47, was fitted with three 7.62 mm miniguns firing sideways from its left windows; the pilot flew a steady circle around the target, aiming with a sight in his side window, and could saturate an area the size of a football field. Officially the AC-47, call sign “Spooky”, it was nicknamed “Puff the Magic Dragon” for the stream of tracer it poured down at night. From 1965 Spooky gunships defended outposts and hamlets under night attack. They were followed by the AC-119 and the AC-130, which hunted trucks on the Trail with sensors and cannon.

Ranch Hand and Agent Orange

The most lasting part of the air war was the least violent at the time. Operation Ranch Hand, the Air Force’s herbicide program, began flying operational missions in January 1962, at the request of the South Vietnamese government and with Kennedy’s approval. Its purposes were to strip the jungle canopy along roads, rivers, base perimeters and the borders, so that ambushes and infiltration routes could be seen from the air, and to destroy crops in areas controlled by the Viet Cong. The crews flew modified C-123 transports, at first UC-123Bs and later UC-123Ks, at treetop height, spraying in formation; their unofficial motto was a play on the Forest Service slogan, “Only You Can Prevent Forests.” Army helicopters and Navy boats sprayed base perimeters and riverbanks.

The Institute of Medicine’s review of the military records found that 17.6 million gallons of herbicides were sprayed between August 1965 and February 1971 over about 3.6 million acres, and that Agent Orange, named for the orange stripe on its drums, accounted for 11,261,429 gallons, about 61 percent of recorded use. Later research by Jeanne Stellman and colleagues (2003) revised the total for 1961–71 upward, to about 19.5 million gallons. Agent Orange, a mixture of two herbicides, was contaminated in manufacture with 2,3,7,8-TCDD, the most toxic form of dioxin. Concern about health effects, at first on birth defects, led to the end of the program: the last fixed-wing Ranch Hand mission flew in early 1971, and the last American herbicide operation by helicopter on 31 October 1971.

Adm. Elmo R. Zumwalt Jr., who as commander of naval forces in Vietnam ordered the defoliation of the riverbanks of the Mekong Delta to protect his boat crews, later came to believe that his son, Lt. Elmo Zumwalt III, a Swift boat commander who died of cancer in 1988, had been harmed by the spraying he had ordered. Vietnamese government and Red Cross figures put the number of Vietnamese exposed in the millions and the number affected by related illnesses and birth defects also in the millions; these claims are disputed and difficult to verify independently. The long legal and medical history of Agent Orange in the United States, from the 1984 class-action settlement to the Agent Orange Act of 1991 and the PACT Act of 2022, is told in Chapter 9.

Linebacker I: the Easter Offensive and the Mining of Haiphong, 1972

By 1972 most American ground forces had gone home (Chapter 8). On 30 March North Vietnam launched its largest offensive of the war, the Easter Offensive, with tanks and heavy artillery, across the DMZ, into the Central Highlands and toward An Lộc north of Saigon. Nixon responded with air power, which was what remained. The Air Force and the Navy rushed squadrons back to Southeast Asia; Seymour Johnson’s 4th Tactical Fighter Wing was among the units that began rotating to Thailand that year. On 8 May Nixon announced the mining of North Vietnam’s ports, and Navy A-6s and A-7s from USS Coral Sea laid mines in the approaches to Haiphong, closing the harbour through which most Soviet supplies arrived, something Johnson had never permitted.

Operation Linebacker, later Linebacker I, ran from 10 May to 23 October 1972. It was different from Rolling Thunder in two ways. Nixon gave the commanders far more freedom to choose targets, including those around Hanoi and Haiphong. And the Air Force now had laser-guided bombs: on 13 May F-4s of the 8th Tactical Fighter Wing dropped the Thanh Hóa bridge, the “Dragon’s Jaw”, which had withstood hundreds of sorties since 1965. Linebacker I, together with the stubborn South Vietnamese defence on the ground supported by American advisers and air power, helped stop the Easter Offensive, and in October Hanoi agreed to the outline of a peace settlement. Nixon halted the bombing north of the 20th parallel on 23 October. In the South, meanwhile, the B-52s were used as never before in direct support of a defending army. At An Lộc, besieged from April to June, at Kontum in the Highlands in May, and in the counter-offensive that retook Quảng Trị in September, Arc Light strikes broke up massed PAVN infantry and armour; South Vietnamese commanders and their American advisers credited them with saving all three. The Easter Offensive cost the PAVN very heavily, and the South Vietnamese army, with American air power behind it, held. Whether it could hold without that air power was the question that 1975 would answer (Chapter 9).

Linebacker II: Eleven Days in December 1972

The October agreement fell apart. South Vietnam’s president, Nguyễn Văn Thiệu, refused terms that left North Vietnamese troops in the South; Washington sought changes; Hanoi hardened its position; the talks in Paris broke down on 13 December. On 18 December Nixon ordered Linebacker II, the most concentrated bombing campaign of the war, against Hanoi and Haiphong. Its purpose, in the words of an Air Force history, was to use the heavy bombers in their intended role, “concentrated strategic bombardment.” For eleven days, with a 36-hour pause over Christmas, B-52s from Andersen and U-Tapao bombed rail yards, power plants, airfields, storage areas and SAM sites by night, and Air Force and Navy fighter-bombers struck by day.

The Air Force Historical Support Division gives about 700 B-52 night sorties and 650 daytime fighter and attack strikes; the Andersen history gives 729 B-52 sorties. Twenty-six American aircraft were lost: 15 B-52s, 2 F-4s, 2 F-111s and an HH-53 rescue helicopter of the Air Force, and 2 A-7s, 2 A-6s, an RA-5 and an F-4 of the Navy. Seventeen of them fell to SA-2s, three to MiGs, three to guns and three to unknown causes. The B-52s, flying the same routes, altitudes and timings on the first three nights, suffered most on the third night, 20 December, when six were shot down; after that the tactics were changed, with routes, altitudes and timing varied and the attacks compressed. The 15 B-52s carried 92 crewmen; by the Air Force’s count, 33 became prisoners of war, 25 were missing and 8 were killed or died of wounds, and 26 were recovered. The National Museum of the US Air Force gives more than 15,000 tons of bombs dropped.

The talks resumed in Paris on 8 January 1973, and the agreement was signed on 27 January. What the bombing achieved is still argued. The Air Force fact sheet concludes that it caused severe damage to North Vietnam’s logistics and war-support capability, and Nixon and many air commanders held that it forced Hanoi to sign. Critics, and many historians, note that the January agreement differed little from the October draft; in their view the bombing was aimed as much at reassuring Thiệu, and at persuading him to accept a settlement, as at coercing Hanoi. North Vietnam counted the campaign a victory, the “Điện Biên Phủ in the air”, and reported heavy civilian casualties; the Bạch Mai hospital in Hanoi was hit on 22 December. Both sides could claim something; neither the bombing nor the agreement settled the war, which ended on the ground in 1975.

The Air War in the Balance

The air war shows the reach and the limits of American power in Vietnam more clearly than any other part of it. American aircraft could go anywhere in Indochina, drop more bombs than had fallen in any previous war, carry an army into battle and bring its wounded to a surgeon within the hour. They could not, in Rolling Thunder, persuade a government willing to accept immense punishment to abandon the war in the South, or stop the flow of men and supplies down the Trail. When the political goal was narrower, in 1972, to stop an invasion that had to move in the open on roads, and to force a settlement that let the Americans leave, air power did more. The costs fell on all sides: on the aircrews, on the North Vietnamese and Laotians beneath the bombs, and, through the herbicides, on Americans and Vietnamese for decades after the last aircraft flew home. The ground war that the bombing was meant to support is in Chapter 4; the year it reached its crisis, 1968, is in Chapter 6.