The attack on Tan Son Nhut Air Base, headquarters of the Republic of Vietnam Air Force (VNAF) and the United States Air Force (USAF) 7th Air Force, occurred during the early hours of 31 January 1968. Tan Son Nhut Air Base was one of the major air bases used for offensive air operations within South Vietnam and for the support of United States Army and Army of the Republic of Vietnam (ARVN) ground operations. The attack by Vietcong (VC) and People's Army of Vietnam (PAVN) forces was one of several major attacks on Saigon in the first days of the Tet Offensive. The attack was repulsed with the VC/PAVN suffering heavy losses; only superficial damage was done to the base.

Background The United States had been providing material support to South Vietnam since its foundation in 1954. The Vietnam War effectively began with the start of the North Vietnamese backed VC insurgency in 1959/60 and the U.S. increased its military aid and advisory support to South Vietnam in response. With the worsening military and political situation in South Vietnam, the U.S. increasingly became directly involved in the conflict. U.S. ground troops were first deployed to South Vietnam in March 1965 and by the end of that year almost 200,000 U.S. military personnel were deployed and were engaging in combat with the PAVN/VC. The growing U.S. presence was matched by North Vietnam and the U.S. and its allies increasingly took over fighting the PAVN/VC main force units from the Army of the Republic of Vietnam (ARVN), relegating them to pacification; fighting the war in the villages with the VC. The U.S. strategy was one of attrition warfare and they conducted hundreds of search and destroy operations to engage the PAVN/VC, but the PAVN/VC were usually able to control the location and timing of engagements to offset U.S. tactical advantages. A number of large, but essentially inconclusive, battles took place throughout 1966 and 1967. By late 1967 Military Assistance Command, Vietnam (MACV) claimed that every statistical indicator of progress showed that its strategy was succeeding.

With the buildup of U.S. ground forces in South Vietnam came massive infrastructure projects to support the logistical requirements of the war. Tan Son Nhut was eclipsed as the country's major air base by other large jet capable airfields, but it remained the primary international civilian airport and the Tan Son Nhut complex hosted a range of important military sites. On the west was the Tan Son Nhut Air Base the headquarters of the VNAF and the USAF 7th Air Force, then there was the civilian air terminal and Air America terminal, to the east was the MACV headquarters and then the South Vietnamese Joint General Staff (JGS) compound.

Defenses and plans Despite the 4 December 1966 VC sapper attack on Tan Son Nhut Air Base, base security was little improved by 1968. The attitude within MACV was that any large-scale VC attack would be detected and defeated before the force reached the base and so the only threat came from small-scale guerilla attacks of fewer than 200 men. The most vulnerable areas of the base were the sparsely populated western and northern perimeters where VC forces could assemble unnoticed and these were protected by old, largely ineffective, Japanese and French minefields, then three layers of concertina wire and a perimeter fence. Within the base, the 1,000 man USAF 377th Security Police Squadron (377th SPS) was responsible for base defense. They divided the base into six sectors and manned more than 50 observation towers and bunkers around the 20 km long inner perimeter of the base. Each sector had two machine gun armed jeeps and there were 14 13-man quick reactions teams ready to reach any point on the perimeter within 12 minutes. In an emergency the 377th SPS would also take operational control of Task Force 35 (TF 35), an ad hoc three-platoon collection of men from U.S. Army support units on the base. In addition the VNAF 2nd Service Battalion also shared responsibility for the defense of the base.

With its dual use as a civilian/military airfield and large numbers of Vietnamese workers on the base, it was easy for the VC to gain intelligence as to the base defenses. An old cemetery on the western perimeter was accessible to Vietnamese and an increase in visits and burials there was noted in the leadup to the attack. The 377th SPS regarded the western perimeter, designated Echo Sector, as the most vulnerable sector of the base as it was closest to the Delta Sector flightline, whereas any attack from the north would have to cross 4 km of open ground, including both runways, before reaching the flightline.

Central Office for South Vietnam gave responsibility for the attack to the 9th Division commander – Col. Nguyễn Thế Truyện (alias Năm Truyện) with a 2,665-man force: the 271st Main Force (MF) Regiment from his division, plus four attached battalions, the 2nd Independent Battalion, the D-16 Battalion, the 267th and 269th MF Battalions. The cadres in these units were southerners, but due to casualties, about half of the soldiers were fillers from the North. Truyện's plan called for the D-16 Battalion to occupy the Vinatexco textile mill () on Highway 1 (now Route 22/Trường Chinh), which ran along the west perimeter of the base, approximately 1 km north of the 051 Gate (), the planned entry point. The Vinatexco Mill would form the headquarters for the attack. The 269th MF Battalion would lead the attack on the 051 Gate, followed by the 267th MF Battalion which would exploit the opening and then the 1st Battalion, 271st Regiment would attack the flightline and base facilities.

The Tết ceasefire began on 29 January, but was cancelled on 30 January after the VC/PAVN prematurely launched attacks on II Corps and at 17:30 the 7th Air Force commander General William W. Momyer ordered all air bases in South Vietnam to security condition red. On the night of 30/31 January, Truyện's forces marched into their attack positions, undetected by the ARVN 53rd Regional Force Battalion responsible for security outside the perimeter north and west of the base.

Battle

Attack

At approximately 03:20 on 31 January, the VC launched a series of diversionary attacks by fire on the north-eastern perimeter of the base with tracer rounds aimed at the petroleum, oil and lubricants storage tanks northeast of the north runway. The VC also fired on Gate 1, the main gate of the base. At approximately 03:30, an observer in the Tango 4 tower 15m from the 051 Gate at the western end of the base reported mortar fire on the western perimeter fence with VC forces assembling in the village west of the fence. The "mortar rounds" were actually Bangalore torpedoes and satchel charges used to blow holes in the concertina wire and perimeter fence and the VC were soon entering the base.

At the 051 Bunker () 200m south of the 051 Gate, the five-man team poured flanking fire onto the VC/PAVN with their M60 machine gun on the sandbagged rooftop and with their rifles, but the VC soon responded with a barrage of RPG-2 and mortar fire, forcing the Security Policemen inside the bunker and to call for help. A gun jeep was sent to assess the situation in Echo Sector, but was stopped by heavy fire near the northeast corner of the base and reported large numbers of VC coming through the 051 Gate. By 03:45, the VC had overrun the 051 Bunker, killing four of the five men inside and severely wounding the survivor. A patrol from the ARVN 53rd Regional Forces reported that a further one or two battalions were waiting near the Vinatexco Mill to join the assault.

Several Echo Sector quick reaction teams were sent to the 051 Gate and the 051 Bunker while four UH-1C Huey gunships of the U.S. Army's 4th Platoon, 120th Assault Helicopter Company, 1st Aviation Brigade arrived over Echo Sector and began dropping flares and engaging the VC with rocket and machine-gun fire. At the Central Security Control (CSC) there was limited information as to the size of the VC attack, but the situation at the 051 Gate was seen as critical and 377th SPS Operations Officer Major Carl Bender ordered a platoon from TF 35 (composed mostly of men from the 1st Signal Brigade) to reinforce the quick reaction teams that had formed a skirmish line 250m east of the gate on the east side of the Whiskey 8 north-south taxiway. Not being trained infantry, the TF 35 troops were inexperienced and nervous, with a two-man machine gun team being killed when they advanced towards the VC and others almost firing on friendly troops. A second platoon from TF 35 soon arrived to join the skirmish line. Further south, VC forces had reached the flightline and placed satchel charges under VNAF C-47s, damaging 14 of them before being forced back by the Delta Sector quick reaction team.

The VC were unable to cross the exposed Whiskey 8 taxiway and the U.S. forces there were now being constantly reinforced and resupplied. A composite group of VNAF and ARVN forces joined on the south of the line together with three M41 light tanks and the U.S. and South Vietnamese forces then formed a horseshoe defence, pouring fire on the VC from multiple directions. Two of the M41s were knocked out by RPGs, and the commander of the VNAF 33rd Tactical Wing – Lt. Col. Lưu Kim Cương was shot in the leg but remained in command of his forces. A ten-man VC squad tried to outflank the line but was stalked by Bender, who progressively shot the last VC in line, killing eight and breaking up the flanking manoeuvre. Meanwhile, the ARVN 8th Airborne Battalion that was at the base waiting for transport north to Khe Sanh Combat Base were committed to the battle, arriving in Echo Sector to begin a counterattack following a preparatory artillery bombardment.

Counter-attack At dawn, the VC began to withdraw through holes in the perimeter fence near the 051 Bunker. The ARVN Airborne began their advance towards the perimeter in a skirmish line, but as they did so they were fired on from behind by VC who were lying in the long grass or sheltering in the cemetery, killing or wounding 18 ARVN soldiers. The Airborne then regrouped and began engaging the VC.

When the base perimeter had originally been breached, Lieutenant Colonel Jack Garred, the senior advisor to the South Vietnamese Tan Son Nhut Security Forces, requested a U.S. Army Brigade to secure the western flank of the base. II Field Force, Vietnam ordered the 25th Infantry Division at Củ Chi Base Camp, 24 km north of Tan Son Nhut, to send an armored cavalry troop to Hóc Môn District to cut off the anticipated VC route of withdrawal from Tan Son Nhut. At 04:15, the mission was assigned to Lieutenant Colonel Glenn K. Otis's 3rd Squadron, 4th Cavalry Regiment. Otis assigned the mission to his only available forces at Củ Chi, two platoons of Troop C commanded by Captain Leo Virant with a strength of three M48 tanks and ten M113 Armored Cavalry Assault Vehicles (ACAVs). As Troop C left their base at 05:03, the mission was changed from securing Hóc Môn to counterattacking the VC at Tan Son Nhut. Virant left the base by a side entrance to avoid Củ Chi village, which was under attack by the VC, and followed secondary roads rather than Highway 1 to avoid mines and ambushes, while Otis flew overhead in a UH-1 which dropped flares along the route. At dawn Otis's UH-1 returned to Củ Chi to refuel and after crossing the Hóc Môn Bridge the unit came under the control of the Capital Military District and Virant contacted Garred at the base who sent an ARVN officer to meet Troop C and guide them to the battle area. However, the ARVN officer was unable to provide any useful tactical information. Garred ordered Virant to move down the west perimeter of the base and fire on anything west of the base, but was unable to provide any information on VC strength or dispositions. Placing an M48 at the head of the column, Virant followed directly behind in his command ACAV.