Phou Pha Thi is a remote mountain in Houaphanh Province, northeastern Laos. The mountain, which is about 1,700 meters (5,600 ft) high, is located within the former Royal Lao Army's Military Region 2, and about 24 kilometers (15 mi) from the border of the Democratic Republic of Vietnam and 48 kilometers (30 mi) away from Sam Neua, the Pathet Lao capital. For the local Hmong and Yeo tribes that lived in the area, Phou Pha Thi was a place of religious significance. They believed it was inhabited by spirits possessing supernatural powers to exercise control over their lives. However, the United States Air Force (USAF) saw Phou Pha Thi as an ideal location for installing a radar navigation system to assist U.S. pilots in their bombing campaigns in North Vietnam, and along the Ho Chi Minh Trail inside Laos.[1]