With a Khmer Rouge victory imminent, the US government made contingency plans for the evacuation of US nationals and allied Cambodians by helicopter to ships in the Gulf of Thailand.

At the beginning of 1975 the Khmer Republic, a United States-supported military government, controlled only the Phnom Penh area and a string of towns along the Mekong River that provided the crucial supply route for food and munitions coming upriver from South Vietnam.

As part of their 1975 dry season offensive, rather than renewing their frontal attacks on Phnom Penh, the Khmer Rouge set out to cut off the crucial Mekong supply route.

On 27 January, seven vessels limped into Phnom Penh, the survivors of a 16-ship convoy that had come under attack over the 100 kilometres (62 mi) journey from the South Vietnamese border.

On 3 February a convoy heading downriver hit naval mines laid by the Khmer Rouge at Phu My approximately 74 kilometres (46 mi) from Phnom Penh.

[5]: 138 On 6 January 1975, CINCPAC placed the 31st Marine Amphibious Unit on 96-hour alert to move the evacuation fleet into position off Kampong Som (previously Sihanoukville) in the Gulf of Thailand for the implementation of Operation Eagle Pull.

[3]: 110 On 3 April, given the deterioration in the defences around Phnom Penh, Ambassador John Gunther Dean requested the deployment of the 10-man Operation Eagle Pull command element which landed at Pochentong on a BirdAir C-130 plane.

As the Khmer Rouge controlled the east bank of the Mekong opposite Phnom Penh, the command group selected LZ Hotel, a soccer field about 900 metres (3,000 ft) north-east of the embassy.

[3]: 114  Prince Sirik Matak, a former prime minister and a driving force behind the formation of the Khmer Republic rejected the offer of evacuation and said to Ambassador Dean that "I have committed this mistake of believing in you, the Americans.

[3]: 114–115  The command group then proceeded to make contact with "King Bird", an orbiting HC-130 plane of the 56th Aerospace Rescue and Recovery Squadron, that would control the flow of the helicopters.

At 07:43 the first group of helicopters crossed the Cambodian coastline and about one hour later, after traversing 160 kilometres (99 mi) of hostile territory, the initial wave set down on LZ Hotel and the Marines quickly established a defensive perimeter.

As LZ Hotel could only hold three CH-53s at any time, flights arriving after the initial build-up had to be held at Point Oscar, some 50 kilometres (31 mi) south of Phnom Penh until called in by "King Bird".

The FACs immediately made low passes over the east bank of the Mekong, but could not spot any fire coming from known enemy positions in that location.

[3]: 123 At 11:15, the two USAF HH-53 Super Jolly Green Giants returned as scheduled, and successfully extracted the Combat Control Team and the Eagle Pull command element.

These three Jolly Green Giants had been flying a precautionary search and rescue orbit just north of Phnom Penh during the entire operation in case any of the participating aircraft ran into trouble.

[3]: 123–124 On 13 April, the evacuees were flown to U-Tapao Air Base in Thailand on HMH-462 helicopters and Amphibious Ready Group Alpha proceeded to the South China Sea to rendezvous with Task Force 76 as it stood by to implement Operation Frequent Wind, the evacuation of Saigon.

[3]: 124 Henry Kissinger observed in his Vietnam War memoir that the Ford Administration was astonished and shamed by the fact that top Cambodian officials refused to leave the country.