Moving into the vacuum left by the departing French, the United States began providing military and financial support to the Royal Lao Government.

[1] From 1961 until the war's end in February 1973, the Central Intelligence Agency (CIA), the CIA-raised guerrillas of L'Armée Clandestine would resist the invading People's Army of Vietnam.

[2][3] Operation Phou Phiang II had ended with the People's Army of Vietnam (PAVN) within striking distance of the Royalist guerrilla headquarters at Long Tieng on the Plain of Jars.

As if that were not worrisome enough to the Royal Lao Government, on 12 December, infiltrating PAVN troops again struck the vital guerrilla base at Long Tieng.

U.S. Air Force AC-130 Spectre gunships, F-4 Phantom IIs, and A-7 Corsairs struck targets of opportunity in the Communist advance.

[4][5] After a week of suffering casualties from air strikes, the PAVN forces withdrew, taking a route past the northern outpost at Bouamlong as they did so.

A follow-up operation, Phou Phiang III, was designed to relieve Bouamlong, as well as reduce the threat to Long Tieng.

As the result of a 17 December conference on the matter, an intelligence data base was developed of locations of past usage of Communist 122mm and 130mm field guns.

[6] On 18 January 1973, the task force left the village of Ban Na in the hills and headed eastward towards the Jungle's Mouth.

A Commando Raiders team was helicoptered in to secure a landing zone eight kilometers southeast of the Moung Soui airfield.

Having only 81mm mortars for reply, and lacking bunkers for cover, the Thais moved north out of range, further opening the pincers and giving PAVN maneuver room.