The United States went to war with North Vietnam as a result of the Cold War and its policy of containment. The underlying reason was the fear of the spread of communism. The United States believed that North Vietnam, which was led by a communist government, posed a threat to the stability and security of South Vietnam and other countries in Southeast Asia. Additionally, the United States had a commitment to South Vietnam, which was seen as a key ally against communism in the region. Therefore, to prevent the spread of communism and to support South Vietnam, the United States decided to go to war with North Vietnam.
