Which 1964 action led Congress to grant broad authority for U.S. involvement in Vietnam?

• A. Gulf of Tonkin Resolution
• B. Potsdam Agreement
• C. Moscow Treaty
• D. Napoleonic Accord

Answer: (A)

The key idea is that Congress gave the president broad power to wage war in Vietnam after a major incident in the Gulf of Tonkin. In August 1964, events near North Vietnam led to a quick congressional response, resulting in a resolution that authorized the president to use all necessary means to defend Southeast Asia. This effectively blank-checked the executive branch, allowing rapid escalation of U.S. involvement—air strikes, military advisers, and eventually ground troops—without a formal declaration of war. The other options refer to events or agreements from different times and contexts, so they don’t fit the idea of Congress granting wide authority to engage in Vietnam in 1964.