Operation Phiboonpol

Operation Phiboonpol (9–11 June 1971) was a "short but very intense engagement" of the Laotian Civil War. Five Royal Lao Government battalions went on the offensive in Military Region 4 of the Kingdom of Laos to try to regain the Boloven Plateau, which overlooked the vital Ho Chi Minh Trail lying to its east. Stopped in its tracks by the People's Army of Vietnam, with its first use of tanks in southern Laos, the Royalists held firm while close air support inflicted heavy casualties on North Vietnamese attackers. A Thai mercenary company sent as a Royalist relief force was ambushed and wiped out. For weeks after the battle, vultures feasted on unburied corpses.

The Ho Chi Minh Trail has been called, "the lifeline of Hanoi's [North Vietnam's] efforts to topple the South Vietnamese government." There were numerous attempts by Royal Lao Government troops—in most cases, irregular military units—to interdict the Trail during the course of the Second Indochina War. Beginning with offensives such as Operation Left Jab and Operation Junction City Jr. in 1969, the Central Intelligence Agency (CIA) continued to direct attacks on the Trail in 1970 in Operation Maeng Da, Operation Honorable Dragon, Operation Diamond Arrow, and the Tchepone Operation. Action against the Trail continued in 1971 with Operation Silver Buckle, Operation Desert Rat, and Operation Phoutah. From the eastern side of the Trail came Operation Lam Son 719 on 8 February 1971.