Kennedy and Diem were both killed in 1963 and 1964. Johnson took control of the situation by increasing the amount of money and manpower put into Vietnam. Congress passed the Gulf of Tonkin Resolution, giving the president full military power. After Johnson dramatically escalated the amount of soldiers in Vietnam, The North Vietnamese mounted a surprise attack during the Vietnamese new year, and this strike was called the Tet Offensive. It made America more aware of what they were up against, that the communists were capable of fierce, guerrilla warfare, unlike anything Americans had ever fought before. Images of the terror and disarray reached back home, and the U.S. began to wonder how effective their involvement in Vietnam really was.