[2]: 109–10 The Marines together with the Airborne formed the South Vietnamese general reserve and had a significant political role to play in Saigon.

The general reserve troops represented the real muscle of the Saigon-based Directory members and also constituted a balance of power between the rival officer cliques.

[3]: 24 In July 1965 COMUSMACV General William Westmoreland described the performance of the marines as disappointing, a problem he traced to Khang, "a poor leader [with]... influential political connections.

[3]: 256 He was awarded the Silver Star for valor June 27 – 29, 1967 by the President of the United States, Lyndon Johnson, and was described by General Wallace M. Greene as "as one of the finest field commanders in Asia."

Appearing to both fear and respect Khang, he admitted to US Ambassador Ellsworth Bunker that "unfortunately we do not have many real generals who know how to command more than a division," including, he added, himself.

In early June 1968 Khang resigned his Corps command after misplaced US helicopter rocket fire killed several Kỳ supporters observing fighting in Saigon during the May Offensive.