US Congress repeals Gulf of Tonkin Resolution

By 1967, the rationale for what had become a costly U.S. involvement In the Vietnam War was receiving close scrutiny. With opposition to the war mounting, a movement to repeal the resolution—which war critics decried as having given the Johnson administration a "blank check"—began to gather steam.

An investigation by the Senate Foreign Relations Committee revealed that Maddox had been on an electronic intelligence collection mission off the North Vietnamese coast. It also learned that the U.S. Naval Communication Center in the Philippine Islands, in reviewing ships' messages, had questioned whether any second attack had actually occurred.

Mounting public opinion against the war eventually led to the repeal of the resolution, which was attached to the Foreign Military Sales Act that Nixon signed in January 1971. Seeking to restore limits on presidential authority to engage U.S. forces without a formal declaration of war, Congress passed the War Powers Resolution in 1973, over Nixon's veto. The War Powers Resolution, which is still in effect, sets forth certain requirements for the President to consult with Congress in regard to decisions that engage U.S. forces in hostilities or imminent hostilities.