A captain who spent two and one-half years with SF in Nam before losing a leg in combat, wrote of the Nungs:
My first tour was with the Mike Force, working with the Nung tribesmen, mostly out of Nha Trang, before they became the Mobil Strike Forces assigned to each of the four corps areas. These were the soldiers that later went on to the projects - Omega, Sigma, and the rest.
The Mike Force was a kind of “in-house” program developed by SF. Normally the indigenous soldiers in Vietnam varied from okay to very bad - some were almost Viet Cong units. Well, SF had no real way, before the Mike Force, to provide reinforcements if a camp got hit, or to react to any opportunities that might develop. So SF recruited a force from the Nung tribes - a group traditionally hostile to the Vietnamese - who were of ethnic Chinese ancestry and who were essentially mercenaries in the hire of SF.
We trained the Nungs to function very much like an American Army rifle platoon. We gave them a solid basic training program, trained them in reconnaissance, and sent them to SF camps all over the country. We used them very much like a Hatchet Force, thirty-two to about seventy men, loaded with all the food and ammunition they could carry. We used them to relieve places that were under attack or being overrun. They would carry twice the ammo an American would, and went out loaded for bear. And we weren’t planning on bringing any of it back with us, either! When it came to carrying bullets or food, bullets were better.
The regular Vietnamese army units were so often infiltrated by Viet Cong that they were quite unreliable in combat, but the Nungs were extremely loyal to SF. When we used them, we sent them in fast; they did what they were supposed to do, and then we pulled them back out again quickly.