The war that involved the United States' military engagement in Vietnam during the 1960s was the Vietnam War, also known as the Second Indochina War. This conflict primarily stemmed from the Cold War context, with the U.S. seeking to prevent the spread of communism in Southeast Asia, supporting the government in South Vietnam against the communist North, and ultimately the Viet Cong. The war escalated significantly after the Gulf of Tonkin incident in 1964, leading to heavy U.S. military involvement. The Vietnam War became a deeply polarizing conflict in American society, sparking widespread protests and leaving a profound impact on U.S. foreign policy and military strategy.