The Gulf of Tonkin Resolution, passed by Congress in August 1964, granted President Lyndon B. Johnson broad authority to use military force in Vietnam without a formal declaration of war.

This decision followed reported attacks on U.S. naval vessels in the Gulf of Tonkin by North Vietnamese forces. The resolution significantly escalated U.S. involvement in the Vietnam War, leading to the deployment of combat troops and intensified military operations. Critics argue that the resolution was based on misleading information and paved the way for a prolonged and controversial conflict that deeply affected U.S. foreign policy and public opinion.