Phou Pha Thi (Phathi) is a "sacred mountain" in Laos "believed...inhabited by great "phi", or spirits [2] and used for the clandestine Lima Site 85 military installation during the Vietnam War.

The lightly defended installation was destroyed by North Vietnamese attackers in the 10-11 March 1968 Battle of Lima Site 85.

From 1994 to 2004, searches for USAF remains were conducted at the mountain, but few bodies were located.

[2] The site had been used as a military site by French colonialists until seized by the North Vietnamese in 1962,[1] and the Hmong "Secret Army" recaptured the area and a Central Intelligence Agency airstrip was built by 1966.

"Pha-thi mountain...runs from north of the Huoi-san stream to south of the Nam-het River, a distance of about 7,000 meters.