Passed into law on 7 August 1964, the Gulf of Tonkin Resolution was the measure that prompted the expansion of American involvement in the Vietnam War. Also known as the Southeast Asia Resolution, the Gulf of Tonkin Resolution was legislation approved by both the Senate and the House of Representatives in the United States Congress. The joint resolution was signed into law by President Lyndon Johnson.
Just prior to its introduction, a sea battle occurred in the Gulf of Tonkin on 2 August 1964 between the destroyer USS Maddox and the North Vietnamese Navy's Torpedo Squadron 135. Although no American casualties were suffered, one US aircraft was damaged and four North Vietnamese sailors were killed. This was followed two days later by an attack from the USS Maddox and the USS Turner Joy on suspected North Vietnamese boats. Although the event is collectively known as the Gulf of Tonkin Incident, evidence shows that the second attack most likely involved firing on an imaginary enemy since no wreckage or bodies were ever found. Despite this fact, the incident was reported at the time as genuine and became a reason to escalate the conflict.
The Gulf of Tonkin Resolution was not a formal declaration of war. Instead, it gave the commander-in-chief the authorization to use conventional military force in Southeast Asia as he saw fit. President Johnson had already ordered the use of retaliatory air strikes and called for the resolution in a televised address. The passage of the joint resolution itself was simply a formality to give the president full control over the situation without legal problems by conducting a military operation without congressional approval. Specifically, a previous agreement called the Southeast Asia Collective Defense Treaty was now able to be enforced by whatever means the president saw fit.
Very little opposition to the Gulf of Tonkin Resolution occurred in the short time between its introduction and the final vote. Congressman Eugene Siler of Kentucky opposed the measure in the House of Representatives; however, he was not present for the vote. Senators Wayne Morse of Oregon and Ernest Gruening of Arkansas both opposed the escalation in the Senate. Despite these officials fighting against its passage, the Gulf of Tonkin Resolution passed in dramatic fashion, giving the president the ability to begin a major buildup of forces.
Due to the legislation, the conflict in Vietnam continued for another 11 years before the United States finally withdrew during the Fall of Saigon in 1975. The resolution itself was repealed in 1971 with President Richard Nixon. Further limits on presidential war powers were instituted in 1973. Nixon first vetoed the War Powers Resolution in 1973, but he was overridden by Congress, making it a law that remains in effect today.