Later, there were doubts that the second attack had actually occurred. President Lyndon B. Johnson, in an evening address to the nation on Aug. 4, announced he had approved air strikes on North Vietnam and that he would ask Congress to give him a mandate for further action.

On Aug. 7, Congress overwhelmingly passed a joint resolution authorizing LBJ to use “all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression.”

This Gulf of Tonkin Resolution was not a formal declaration of war, but it was the closest approximation that Congress ever provided. It served as a legal basis for a large-scale escalation of US military operations in Southeast Asia.

H.J. RES 1145

Joint Resolution: To promote the maintenance of international peace and security in southeast Asia.

Aug. 7, 1964

Whereas naval units of the Communist regime in Vietnam, in violation of the principles of the Charter of the United Nations and of international law, have deliberately and repeatedly attacked United States naval vessels lawfully present in international waters, and have thereby created a serious threat to international peace; and

Whereas these attacks are part of a deliberate and systematic campaign of aggression that the Communist regime in North Vietnam has been waging against its neighbors and the nations joined with them in the collective defense of their freedom; and

Whereas the United States is assisting the peoples of southeast Asia to protect their freedom and has no territorial, military or political ambitions in that area, but desires only that these peoples should be left in peace to work out their own destinies in their own way: Now, therefore, be it

Resolved by the Senate and House of Representatives of the United States of America in Congress assembled,

That the Congress approves and supports the determination of the President, as Commander in Chief, to take all necessary measures to repel any armed attack against the forces of the United States and to prevent further aggression.

Sec. 2. The United States regards as vital to its national interest and to world peace the maintenance of international peace and security in southeast Asia. Consonant with the Constitution of the United States and the Charter of the United Nations and in accordance with its obligations under the Southeast Asia Collective Defense Treaty, the United States is, therefore, prepared, as the President determines, to take all necessary steps, including the use of armed force, to assist any member or protocol state of the Southeast Asia Collective Defense Treaty requesting assistance in defense of its freedom.

Sec. 3. This resolution shall expire when the President shall determine that the peace and security of the area is reasonably assured by international conditions created by action of the United Nations or otherwise, except that it may be terminated earlier by concurrent resolution of the Congress.
Speaker of the House of Representatives
President pro tempore of the Senate

Statement by the President on the Passage of the Joint Resolution on Southeast Asia

Aug. 7, 1964

The 414-to-nothing House vote and the 88-to-2 Senate vote on the passage of the Joint Resolution on Southeast Asia is a demonstration to all the world of the unity of all Americans. They prove our determination to defend our own forces, to prevent aggression, and to work firmly and steadily for peace and security in the area.

I am sure the American people join me in expressing the deepest appreciation to the leaders and Members of both parties, in both Houses of Congress, for their patriotic, resolute, and rapid action.

Lyndon B. Johnson