The Gulf of Tonkin Resolution or the Southeast Asia Resolution, Pub.L. 88-408, 78 Stat. 384, enacted August 10, 1964, was a joint resolution that the United States Congress passed on August 7, 1964, in response to the Gulf of Tonkin incident.
It is of historical significance because it gave U.S. President Lyndon B. Johnson authorization, without a formal declaration of war by Congress, for the use of "conventional'' military force in Southeast Asia. Specifically, the resolution authorized the President to do whatever necessary in order to assist "any member or protocol state of the Southeast Asia Collective Defense Treaty". This included involving armed forces.