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. There was also entrenched guerrilla subversion throughout the heavily populated coastal regions by the Viet Cong. Consistent with the enthusiasm of Robert McNamara for statistics, Westmoreland placed emphasis on body count and cited the Battle of Ia Drang as evidence the communists were losing. However, the government wished to win at low cost, and policymakers received McNamara's interpretation indicating huge American casualties in prospect, prompting a reassessment of what could be achieved. Moreover, the Battle of Ia Drang was unusual in that US troops brought a large enemy formation to battle. After talking to junior officers General Westmoreland became skeptical about localised concentrated search and destroy sweeps of short duration, because the Communist forces controlled whether there were military engagements, giving an option to simply avoid battle with US forces if the situation warranted it. The alternative of sustained countrywide pacification operations, which would require massive use of US manpower, was never available to Westmoreland, because it was considered politically unacceptable.