2. Gulf of Tonkin Incident: In August 1964, the U.S.S. Maddox, a U.S. destroyer, was allegedly attacked by North Vietnamese torpedo boats in the Gulf of Tonkin. Despite conflicting and uncertain evidence about the alleged attacks, the U.S. Congress passed the Gulf of Tonkin Resolution, which gave President Lyndon B. Johnson broad authority to use military force in Vietnam without a formal declaration of war.
3. Escalation of Military Involvement: The United States initially provided military and financial aid to the South Vietnamese government and sent military advisers to assist and train their troops. As the war progressed, however, the United States became increasingly involved, sending more military advisers and troops, engaging in combat operations, and conducting large-scale bombing campaigns against North Vietnam.
4. Containment Policy: The policy of containment, formulated during the Truman and Eisenhower administrations, aimed to prevent the spread of communism worldwide. By intervening in Vietnam, the United States hoped to limit the expansion of communism in Southeast Asia and prevent its spread to other countries in the region.
5. Cold War Rivalry: The United States and the Soviet Union were engaged in a global contest for geopolitical influence during the Cold War. Vietnam became a key battleground in this ideological conflict, with the United States supporting the anti-communist South Vietnamese government and the Soviet Union backing North Vietnam.