The Democratic Republic of Vietnam's victory depended on the Trail's supply line, located in the Kingdom of Laos.

Ongoing air and ground campaigns sponsored by the United States seeking to sever the Trail had no lasting effect on Communist logistics efforts.

[6] On the evening of 23 October, in a preliminary movement, 50 Commando Raiders were parachuted in from Air America Twin Otters as pathfinders, to secure a landing zone six kilometers southwest of the Communist transshipment point of Lao Ngam.

Savannakhet Unit of the Central Intelligence Agency (CIA) supplied a guerrilla regiment for an aerial invasion.

Groupement Mobile 33 (GM 33), 1,200 strong, rode in on the helicopters of the 21st Special Operations Squadron (21st SOS) early on 23 October.

This pincer movement, centered on Paksong, was dubbed Operation Black Lion V.[7] By 26 November, GM 33 was in Houei Sai.

The 1,580 troops of GM 401 were hopscotched to a landing zone four kilometers northwest of Houei Sai via the helicopters of the 21st SOS.

[7] In early February 1973, two battalions of the PAVN 9th Regiment and some supporting Dac Cong sappers moved south approaching Paksong.

Reports of Communist tanks appearing to stiffen the PAVN advance caused the Thai mercenaries to evacuate the town.