 Savage fighting and the retreat of the communists was immediately followed by the abandonment of the terrain just seized.Combined with this was the anger and frustration engendered among American troops by the effective tactics of the NLF, who conducted a war of sniping, booby traps, mines, and terror against the Americans.As a result of the conference held in Honolulu, President Johnson authorized an increase in troop strength to 429,000 by August 1966.