Nakhon Phanom Royal Thai Navy Base  The Nakhon Phanom Royal Thai Navy Base (NKP), formerly "Nakhon Phanom Royal Thai Air Force Base", is a Royal Thai Navy facility used for riverine patrols along the Mekong River. It is approximately 587 km (365 miles) northeast of Bangkok, 14.5 km (9 miles) west of Nakhon Phanom city in Nakhon Phanom Province in the northeastern region of Thailand, and 411 km (256 miles) from Hanoi in Vietnam. The Mekong River is NKP's border with Laos. The airfield at NKP is jointly used as a civilian airport. Nakhon Phanom Royal Thai Navy Base was established in the 1950s as a RTAF base. The civil war inside Laos and fears of it spreading into Thailand led the Thai government to allow the United States to covertly use five Thai bases beginning in 1961 for the air defence of Thailand and to fly reconnaissance flights over Laos. Under Thailand's "gentleman's agreement" with the United States, Royal Thai Air Force Bases used by the USAF were considered Royal Thai Air Force bases and were commanded by Thai officers. Thai air police controlled access to the bases, along with USAF Security Police, who assisted them in base defence using sentry dogs, observation towers, and machine gun bunkers. All United States Air Force personnel were not fully armed. There were insufficient arms due to the nature of the mission at NKP. Often instructions were given prior to off-base activities to avoid answering questions posed by the press. The USAF forces at Nakhon Phanom were under the command of the United States Pacific Air Forces (PACAF). The APO for NKP was APO San Francisco, 96310  During the Vietnam War NKP was a front-line facility of the Royal Thai Air Force (RTAF) used by the United States in its efforts to defend South Vietnam against insurgency by North Vietnam and the Pathet Lao guerrillas in Laos from 1961 to 1975. Beginning in the late 1950s, North Vietnam began to move troops into areas of eastern Laos in support of the Pathet Lao, and also as a defensive measure to protect their logistical support of the insurgency in South Vietnam. In September 1959, North Vietnam formed Group 959 in Laos with the aim of building the Pathet Lao into a stronger force in its guerrilla war aimed at overthrowing the Royal Lao Government.