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Starting from scratch, North Vietnam created the world’s strongest air defense system, forcing U.S. air power to rise to the Challenge.

On March 2, 1965, 250 U.S. and South Vietnamese aircraft struck two enemy targets near the town of Dong Hoi, just north of the Demilitarized Zone. Operation Rolling Thunder had begun. The U.S. Air Force attacked one of the targets, Xom Bang Ammunition Depot, with 160 aircraft. Five were shot down; four others were damaged. The South Vietnamese air force planes struck the more lightly defended Quang Khe Naval Base with 90 planes. Two were damaged. President Lyndon B. Johnson had ordered the U.S. military on Feb. 24, 1965, to launch the attacks even though assessments by the CIA, Defense Intelligence Agency and State Department’s Intelligence Bureau indicated that bombing alone would not break Hanoi’s will. Unfortunately for Johnson and his advisers, the intelligence analysis turned out to be correct.

North Vietnamese Communist Party leader Le Duan, who consolidated his hold on power in December 1963 by pushing aside Ho Chi Minh and other party officials, was committed to unifying Vietnam rapidly. He placed the military on a wartime footing in July 1964 and sought Chinese and Soviet military assistance. Le Duan received virtually everything he requested. Some aid had already arrived in early 1964. America’s first airstrikes took place on Aug. 5, 1964, as the Johnson administration retaliated for an August 2 torpedo boat attack on a U.S. destroyer in the Gulf of Tonkin. Within days, North Vietnam’s allies began sending advisers, technicians and military equipment to fill Hanoi’s air defense requirement.

The Soviet Union and China had previously established training programs for Vietnamese pilots. The initial group of pilots went to the Soviet Union for instruction in 1956, the year the North Vietnamese air force was founded. Moscow’s advanced jet aircraft training program graduated its first Vietnamese pilots in December 1963. Two months earlier Hanoi had combined the North Vietnamese Air Force and the Air Defense Force under one command that oversaw ground-based anti-aircraft systems.

The Soviet Union delivered 36 MiG-17s in February 1964, and that month North Vietnam formed its first fighter unit, the 921st Sao Dao (Red Star) Fighter Regiment. China provided four Shenyang F-4s (a version of the Soviet MiG-15) and 36 F-5s (MiG-17s) in late August. Airfields capable of handling jets increased from two in 1958 to 33 by December 1964 and to 44 by June 1965.

In September 1964 North Vietnam and China set up a joint air warning system that enabled Hanoi to track air traffic over the Gulf of Tonkin and Laos. By December the North had more than doubled its anti-aircraft batteries and radars. Hanoi brought its air defense systems together in an integrated network in January 1965 and set up the operation’s headquarters at Bac Mai Airfield, where the air force also had its headquarters. One section at the air defense headquarters, the Air Situation Center, processed air defense data. Another section, the Weapons Control Staff, coordinated the response to approaching enemy aircraft and decided which air defense center would take on the attackers. Some 2,600 Soviet air defense personnel, both civilian and military, had arrived undetected by mid-February 1965.

Moscow delivered radar-guided SA-2 surface-to-air missiles to North Vietnam in March, surprising American military leaders, including Rolling Thunder commanders, the Air Force’s 2nd Air Division and the Navy’s aircraft carrier Task Force 77. Ten SAM training centers had been completed by the end of March or early April.

Also in early April, U.S. military officials began making formal requests to strike the SAM locations, but Defense Secretary Robert McNamara rejected those requests. He did not believe the North Vietnamese had the expertise to use the SAMs and figured Soviet technicians in Vietnam would not risk starting a war with the United States by attacking American aircraft. SAM sites with missiles in place became fully operational in July.

The first SAM strike came on July 24, 1965, when an SA-2 downed an Air Force F-4C Phantom II. One crewman was killed, and the other was captured. McNamara then deployed aircraft equipped with radar-jamming equipment to Indochina and agreed to consider retaliatory strikes on a case-by-case basis against the specific SAM sites that attacked U.S. forces. Hanoi, forewarned of the first approved U.S. counterstrikes through its intelligence operations, deployed 120 anti-aircraft guns around each targeted site and moved the SAM batteries to new locations. The guns downed six American aircraft and severely damaged nearly a dozen more.

Three North Vietnamese SAM regiments were active by August 1965, but Soviet domination of the SAM command-and-control systems created potential coordination problems because language differences could trigger launches against friendly aircraft. Hanoi’s air defense headquarters reduced that risk by adding a third section, a bilingual group that translated air surveillance system reports and verified the SAMs’ target identities. The coordination problems gradually decreased as Soviet-trained Vietnamese personnel took over the critical operational positions in the SAM units.

Deadly blast: The warhead of an SA-2 missile detonates as it nears an F-105D, throwing fragments that strike the plane (trailing smoke). The pilot, Capt. Robert M. Elliot, from the 34th Tactical Fighter Squadron, was killed. (U.S. Air Force)


By September 1965 American aviators faced a constantly improving North Vietnamese air defense system. Because most American planes lacked radar warning devices and electronic countermeasures (such as radar-jamming equipment), the pilots had to rely on visually sighting missile launches in time for a “SAM-break” maneuver—a tight turn and dive—to evade the missile. But that meant ditching their bombs and descending into anti-aircraft gunnery range. There they faced increasingly intense fire, starting with heavy guns harassing the incoming flights as they passed, followed by medium and light weapons concentrating on the lead aircraft as the flight got closer to the target. Small-caliber guns engaged the planes as they reached their bomb-release point.

America’s flyers also had to contend with North Vietnam’s fighter pilots who—although outnumbered and technologically handicapped—tried to intercept isolated U.S. aircraft leaving the target area or ambush inbound planes encumbered with bombs. Other North Vietnamese aircraft protected the interceptors from American fighter escorts. As with SAM engagements, the attacked inbound U.S. aircraft ditched their bombs to survive. If errant bombs hit civilians, the tragedy became grist for Hanoi’s propaganda mill.

McNamara’s emphasis on maximizing sorties and bomb tonnage aided Hanoi’s air defense. To achieve more sorties per day, pilots had to fly direct routes to their targets, reducing the distance and flight time. They also needed to fly on fixed schedules with standardized bomb and fuel loads to create an assembly-line efficiency that generated more takeoffs from airfields and launches from carrier decks. But those requirements also precluded the use of deceptive techniques, such as aerial feints, since these increased flight time and fuel consumption, reducing the possible number of sorties and bombings. The rigid, predictable sortie rates and bomb tonnage, a pattern for most of 1964-66, were a gift to Hanoi’s air defenders.

North Vietnam’s knowledge of U.S. air operations went far beyond the predictability of the sortie schedules. From 1965 to 1968 Hanoi consistently acquired 24 to 48 hours’ notice of the daily target list and strike times, enabling its forces to position air defenses around the most critical targets and transit routes. Speculation about the source of that inside information continues to this day, but U.S. commanders in Southeast Asia took aggressive steps to shut off security leaks.

Hanoi also got warnings from Soviet ships monitoring U.S. carriers in the South China Sea. Other alerts came from operatives and listening posts in Laos and near U.S. bases in Thailand and South Vietnam. Those warnings often didn’t reach air defense stations until minutes before the planes appeared on their radarscopes, but combined with the intelligence from other sources, they helped the North Vietnamese identify, track and counter the airstrikes. Ground-control intercept operators often knew the Americans’ weapons and fuel status and shared that information with their pilots.

That advantage was particularly telling from 1965 to mid-1967 when American aircraft were flying into North Vietnamese air space without sufficient aerial surveillance or adequate signals intelligence support. U.S. forces in the Rolling Thunder campaign had only limited radar coverage of North Vietnam’s air space for much of the operation’s first year. They relied primarily on a radar facility atop Monkey Mountain near Da Nang, radar on Navy ships and “airborne early warning” radar on E-1 Tracer planes based on aircraft carriers.

Hanoi’s advantages played a critical role in the early air-to-air engagements. On April 3, 1965, a flight of four MiG-17s from the 921st Fighter Regiment surprised Navy F-8 Crusaders attacking the Tao Bridge and severely damaged one fighter. The next day the North Vietnamese shot down two of four F-105 Thunderchiefs but lost one of their own to the F-100 Super Sabre fighter escorts. EC-121 aircraft, with early warning radar, were deployed to Indochina one month later.

Hanoi learned that the U.S. military had divided North Vietnam into six geographic target zones, called “route packages,” within weeks of the plan’s implementation on Nov. 10, 1965. That same month the Soviet Union delivered MiG-21s, giving the North Vietnamese Air Force its first truly modern fighter-interceptor.

But by the time the pilots were fully qualified on the Soviet jets, Hanoi had begun to lose its intelligence advantage. The U.S. Air Force initiated a drone reconnaissance program in February 1966, and the drones uncovered the SAM operating parameters and tactics. Other improvements in information collection came from covert radar and listening stations in Laos, along with new radars and signals-intelligence equipment on America’s airborne early warning planes.

American aviators also began to employ deception techniques after Air Force Colonel Robin Olds’ Operation Bolo downed five MiG-21s on Jan. 2, 1967. His success inspired commanders to change flight routes and formations to hide the number and types of aircraft and cause confusion about potential targets. Sometimes fighters armed for air-to-air combat flew along routes traditionally used by bombers. All of those changes, combined with other new measures and equipment, paid off in the summer of 1967, when U.S. fighters downed 40 percent of North Vietnam’s fighters, mostly MiG-17s.

The North Vietnamese quickly changed their tactics and became adept at close-in combat maneuvering—something the U.S. had dropped from most of its pilot training programs in the early ’60s. Between October 1967 and May 1968 North Vietnamese MiG-21s downed 16 U.S. aircraft and lost only one. MiG-21s inflicted 22 percent of all U.S. aircraft losses in 1968.

Those North Vietnamese successes spurred the United States to re-institute air combat training and establish fighter schools, such as the Navy’s “Top Gun,” to ensure no opponent would enjoy an advantage in aerial combat.

When the United States brought in new technology, North Vietnam often identified countermeasures and tactics within days of the Americans’ “first use.” For example, SAM units foiled American jamming equipment and new U.S. anti-radiation missiles—which locked on to the radiation emitted by radars at SA-2 sites—by putting the SAM guidance radars in standby mode until the final phases of an engagement. As the Americans developed systems to detect the radars on standby, Hanoi received modifications from Moscow that enabled SAM units to guide the missiles visually to the target. The SAM sites also instituted “mass missile launches” to overwhelm jamming efforts and employed “radar shifting” tactics—connecting multiple radars to a control unit and varying the ones used during an engagement.

But the North Vietnamese never developed successful tactics to counter the Air Force’s SR-71 Blackbird, a supersonic spy plane with radar-absorptive paint that gave it “stealth” characteristics. (See Arsenal, pg. 18.) No North Vietnamese fighters could reach its 100,000-foot operational altitude, and no SAM ever came within 2 miles of damaging one. From its first flight over North Vietnam on March 21, 1968, to its last in 1975, the SR-71’s capabilities and well-planned missions enabled it to operate over North Vietnam with virtual impunity.

Despite the Air Defense Force’s perceived success, Le Duan faced political problems in 1968. Hanoi’s archives indicate that he faced almost open rebellion in the party ranks after that year’s horrendous losses during the Communists’ Tet Offensive, which began January 31 and continued into March. To gain time to reassert his power and rebuild his forces, Le Duan agreed to enter peace talks if the United States ended the Rolling Thunder bombings, which Johnson did on Nov. 2, 1968. Le Duan, however, ordered his negotiators to sign nothing, just keep the talks going. He used the 13-month hiatus in U.S. airstrikes to purge the party’s “dissidents,” repair and enlarge the country’s damaged infrastructure, expand the air force and reinforce the army, particularly the troops going to the South.

Hanoi’s air defense commanders also reorganized. They reduced the number of deployed radars by a third to build a reserve of functioning equipment that could become immediate replacements for losses. They also decommissioned all the heavy anti-aircraft weapons, which had proved ineffective against high-performance aircraft. Some went to coastal defense units, but most were put in storage and their personnel transferred to the ground forces.

Over a third of the light and small-caliber anti-aircraft guns went south to protect ground units against air and helicopter strikes. These moves reduced Hanoi’s home anti-aircraft artillery force from as many as 8,000 weapons of all sizes in 1966 to 862 23-57mm weapons by 1971. However, the North Vietnamese employed deception units to make it appear that three times that number remained in play. More than 5,000 small-caliber weapons, many operated by women and students, were concentrated around the most critical targets.

Upon taking office in January 1969, President Richard Nixon limited air operations over the North to aerial reconnaissance, but he authorized counterstrikes against North Vietnamese forces that fired on the reconnaissance aircraft, delegating regional commanders discretionary authority to strike North Vietnam’s air bases. That forced Hanoi to move fighters to other airfields after landing and replace them with dummy aircraft or planes that were unsalvageable. Civilian volunteers and work crews, including Chinese military engineers, quickly put the bombed airfields back in use, but aircraft maintenance and operational readiness suffered.

Nixon launched Operation Linebacker on May 9, 1972, in retaliation for Hanoi’s Easter Offensive that began on March 30. Linebacker employed B-52 Stratofortress bombers with powerful support that included new tactics, electronic warfare systems and precision-guided bombs, as well as real-time intelligence and surveillance. After some initial successes against the Linebacker strikes, North Vietnam’s air defense fortunes rapidly declined.

Hoping to get another bombing halt, Hanoi invited “pacifists” and sympathizers from around the world to witness the American bombers’ “criminal destruction.” Progress at the Paris peace talks in October 1972 led Nixon to end Linebacker I on October 23. But the North Vietnamese left the negotiating table when talks broke down in December, and Nixon ordered Operation Linebacker II, which began on Dec. 18, 1972.

Linebacker II, America’s largest bombing campaign between World War II and Operation Desert Storm in 1991, included massive B-52 strikes on critical targets in and around Hanoi and Haiphong Harbor. Hanoi again invited “pacifists” to witness America’s inhumane bombing, but Nixon didn’t relent until Hanoi returned to the Paris peace talks and accepted his terms.

The Paris Peace Accords were signed on Jan. 27, 1973. But Le Duan had no intention of honoring the agreement, which removed the bulk of U.S. troops from South Vietnam and enabled him to reconstitute his devastated forces in the South in preparation for the final offensive that captured Saigon on April 30, 1975.

By war’s end North Vietnam had built the world’s densest integrated air defense system, and the American response can still be seen in integrated air campaign procedures, comprehensive battle space management procedures, precision-targeted weapons fired from outside the range of anti-aircraft artillery, paint schemes that make U.S. planes more difficult to spot, tactics to suppress air defenses and intense air-combat training.

Hanoi’s air defenders gained their greatest successes largely because of shortcomings in American planning, policies and operations early in the war. Despite the menace of SAMs and North Vietnamese fighter aces, anti-aircraft guns remained the primary threat to American planes during Rolling Thunder. The later introduction of precision bombing all but eliminated that threat during the Linebacker operations.

The North Vietnamese air defenses’ real success was political, not military. Although the air defense network never threatened American air superiority, it prevented American air power from forcing Hanoi to abandon its plans for conquering South Vietnam. It also weakened America’s political will by reducing the bombing campaign’s accuracy and effectiveness while inflicting heavier losses than Americans expected.

North Vietnam’s Air Defense Force was but one component of a comprehensive war strategy directed at a single objective—unifying Vietnam under Hanoi’s rule. As long as Le Duan enjoyed Chinese and Soviet support, only invasion, his army’s total destruction or his removal from power would force him to abandon unification. Hanoi modified military and diplomatic tactics in response to American actions and technology, but the strategic objective remained unchanged. Negotiations were offered only to gain time to prepare for the next step toward conquering South Vietnam.

If Johnson had ramped up his Rolling Thunder operation before or during the 1968 Tet Offensive and bombed North Vietnam with the force of Linebacker II, the combination of an effective bombing campaign and devastating troop losses might have forced Le Duan to sign a peace agreement earlier. Le Duan likely would have ignored that agreement too; however, it seems unlikely that the Johnson administration and Saigon regime would have completed the economic and political reforms needed to withstand a Communist assault.

Thus, the ultimate outcome of the war would probably have been the same as it was in 1975. But America’s large-scale involvement would have ended much sooner, saving thousands of lives and billions of dollars.

Historians may debate whether the United States should have resumed the bombing or continued supporting Saigon when North Vietnam breached the 1973 peace agreement, but renewed bombing was unlikely because America had lost its will to continue the war. South Vietnam’s political shortcomings and its long, almost indefensible border also would have complicated any attempts at a sustained defense. What’s more, another U.S. intervention risked a negative reaction in the international community and a response from China and Russia that could have harmed diplomatic initiatives to improve relations with those countries.

North Vietnam’s leaders entered the war with a strategy, a thorough knowledge of their opponent, a complete understanding of the resources required to achieve their objective and a willingness to do whatever it took to win. America’s most senior leaders understood neither their enemy nor the impact of their operational restrictions on U.S. forces. 

Carl O. Schuster is a retired Navy captain with 25 years of service. He finished his career as anintelligence officer. Schuster, who lives in Honolulu,is a teacher in Hawaii Pacific University’s Diplomacy and Military Science program. He wrote “The Rise of North Vietnam’s Air Defenses” in the June 2016 issue.

First published in Vietnam Magazine’s August 2016 issue.