AAA Anti-Aircraft Artillery

The air defense force, with 6 AA and 2 radar regiments in 1963, grew rapidly from 1965 onwards. In 1964 there were about 700 AA weapons of all types and 20 early warning radar sets. Air defense was limited to key population or military sites and effective at heights of 20,000 feet or lower. In September 1964, the DRV had only fourteen hundred anti-aircraft guns, 22 early warning, and four fire-control radars.

At the time of the first Gulf of Tonkin incident in early August 1964, the DRV made a direct and unsuccessful request for military assistance (unspecified) from the Soviet Union. The material requested is likely to have included anti-aircraft weapons, and three months after Khrushchev's ouster these began to be forthcoming. In January 1965 aerial photography established the presence of Soviet self-propelled anti-aircraft guns in North Vietnam for the first time; these weapons may have been delivered by a Soviet cargo ship which arrived in Haiphong on 22 December 1964. There was a major expansion in AA gun and radar strength and capability (2100 AA weapons by February 1965, for example).

Below 2,000 feet, small arms were the most serious threat, but US directives limiting most operations to altitudes above 4,500 feet, the maximum effective altitude of small arms fire, limited the effect of these weapons. Other weapons included 14.5mm, 37mm, 57mm, 85mm, and l00mm gun batteries, with effective altitude coverage up to 45,000 feet. The effectiveness of these weapons varied with gun concentration, weather, and the type of attack flown by the aircraft aimed fire, Evasive action by US aircraft limited the effect of most fire encountered by US aircraft was barrage type, where the defenders simply put up a wall of flak in front of the attacking aircraft. The AAA was most effective if the cloud bases were below 8,000 feet, as this allowed the gunners to set the fuzing of the shells more accurately at the same time that aircraft vertical maneuvering was restricted by the clouds.

American aviation began carrying out systematic raids, both day and night, against the DRV since 7 February 1965. To achieve their goals, in 1966 the Americans increased the intensity of their aircraft raids by a factor of more than one and one-half. If, in 1965 more than thirty thousand aircraft sorties were carried out over the territory of the DV, then, from 1966 to February 1967, there were more than fifty thousand sorties. Every twenty-four hours an averaae of up to 160 aircraft sorties, and on some days up to 300, were carried out over the DRV to deliver bombing strikes, to conduct aerial reconnaissance, and to cover strike groups of attack aviation. In all, for two years, American aviation carried out over eighty thousand aircraft sorties over the DRV. Included in that total were approximately 9000 bombing strikes against various targets in DRV territory. As a result of these strikes more than 800 installations were completely or partially destroyed.

The intensive combat actions of American aviation, the constant change in its tactical methods, the use of new methods of neutralizing air defense means, and, also, the strengthening and improvement in air defense, exerted an influence on the change of tactics in the air defense of the DRV as a whole.

From the initial repulse of the first American air raids, the VPA command did not establish the mission of direct cover for important installations in the country. The basic purpose underlying the combat use of air defense troops was to destroy the maximum number of US aircraft and thereby sustain high morale among the Vietnamese people and their army. As a result of this mission, the tactics for using antiaircraft means led to wideranging movements of subunits for the purpose of organizing "ambushes" on the probable flight axes (routes) of American aircraft.

In accordance with this, during the first half of 1965, antiaircraft artillery and machine gun units and subunits usually occupied positions in line formation along the favorite flight paths of the targets. After firing on the aircraft, subunits would receive 'a new task and depart for a different area. Such a "guerrilla" method of combat with the air enemy from "ambushes" with frequent changes of firing positions allowed the downing of US aircraft with a small number of antiaircraft artillery and machine-gun subunits.

Subsequently the Americans changed tactics. Aircraft began to fly around the "ambushes" and to deliver more effective strikes against exposed installations. This then forced a change in air defense tactics -- a change to an organized all-around defense of installations with the simultaneous use of "ambushes" along the approaches to important installations. They started to allocate complete antiaircraft artillery units to the "ambushes," deployed six to five kilometers from the installations on the most probable axes of approach by American aircraft.