It took place in the port of Saigon in the early hours of 2 May 1964, and was mounted by commandos from the 65th Special Operations Group (Vietnamese: Đội Biệt động 65).

Shortly after midnight on 2 May 1964, two Viet Cong commandos climbed out of the sewer tunnel near the area where Card was anchored, and they attached two loads of explosives to the ship's hull.

On 15 December 1961, USNS Card left Quonset Point, Rhode Island, with a cargo of H-21 Shawnee helicopters and U.S. soldiers from Fort Devens, Massachusetts, bound for Vietnam.

At Subic Bay in the Philippines, the cargo and troops were transferred to USS Princeton, which arrived and unloaded off the coast of Đà Nẵng the following month.

[3] From 1961 onwards, Card and USNS Core regularly docked in Saigon to unload heavy artillery, M113 armored personnel carriers, aircraft, helicopters and ammunition for the South Vietnamese government.

[4]: 11  To facilitate the arrival of Card and other American ships which pulled into Saigon, the South Vietnamese military often deployed navy vessels to conduct patrols around the port, while the surrounding shores were protected by an elite Army of the Republic of Vietnam (ARVN) Airborne battalion.

[4]: 11 The port itself was guarded round the clock by Republic of Vietnam National Police, as undercover South Vietnamese agents operated across the river in the Thủ Thiêm area to disrupt VC activities there.

Undeterred by the level of protection which the South Vietnamese government normally afforded to American ships, Trần Hải Phụng—commander of the Viet Cong's Saigon-Gia Dinh Military District [vi]—ordered the 65th Special Operations Group to attack USNS Card.

So VC members of the 65th Special Operations Group were able to watch US and South Vietnamese military activities at the port, while they were preparing to attack American targets.

[4]: 11  [6] As his unit was assigned with the mission to attack the carrier, Náo took advantage of his position as an employee at the port facility, to reconnoitre Card to design the best strategy to sabotage the ship and all the military hardware on board.

[4]: 12 Náo returned to Saigon and began assembling the equipment required for the attack, which included C4 plastic explosives, TNT, wire, mine detonators and batteries.

[4]: 13 On 1 May 1964, Viet Cong reconnaissance teams spotted USNS Card as it sailed through Gành Rái Bay and entered Lòng Tàu River.

Náo decided to set off the bombs during the early hours of 2 May, so that he and his fellow operative could escape safely and avoid inflicting casualties on the local population.

While awaiting the right time, Náo briefed Hùng on the objectives of the operation, which was to sink the largest American ship at the Saigon Port, and report the results to headquarters.

[7]: 248 In the days that followed, five US Navy divers were deployed to Saigon from the Philippines, in addition to several salvage teams from US bases in Japan and the Military Sea Transport Service Command.

The tugboat USS Tawakoni based at Subic Bay in the Philippines was placed on standby, and later received orders to sail to South Vietnam.

On 20 October 1964, the North Vietnamese government issued a postage stamp which proclaimed an "Aircraft Carrier of America sunk in the Harbor of Saigon", to praise the Viet Cong commandos who carried out the attack.

[12] For the remainder of 1964, the VC launched further attacks on US targets such as the Brinks Hotel and Bien Hoa Air Base, but there were no significant responses from the US military.