 For North Vietnamese military leaders such as Generals Võ Nguyên Giáp and Nguyễn Chí Thanh, the operations carried out by the Americans in South Vietnam had been disastrous for their forces.Furthermore, the military situation in North Vietnam also prompted North Vietnamese leaders to question their war strategy.In 1967 the United States expanded their Rolling Thunder bombing campaign, which enabled American airpower to destroy rather than just threaten Hanoi's limited industrial infrastructure.