 The United States Air Force (USAF) saw Phou Pha Thi as an ideal location for installing a radar navigation system to assist US pilots in their bombing campaigns in North Vietnam, and along the Ho Chi Minh Trail inside Laos.Laos was a neutral country according to the International Agreement on the Neutrality of Laos signed on 23 July 1962.Therefore, the US was prohibited from openly conducting military operations in the kingdom.