 The Gulf of Tonkin incident of 2 August 1964 led to a dramatic increase in direct American participation in the war, with nearly 200,000 troops deployed by the end of the year.Viet Cong and PAVN strategy, organization and structure meant Westmoreland faced a dual threat.Regular North Vietnamese army units infiltrating across the remote border were apparently concentrating to mount an offensive and Westmoreland considered this the danger that had to be tackled immediately.