Gulf of Tonkin incident

The Gulf of Tonkin incident (Vietnamese: Sự kiện Vịnh Bắc Bộ) refers to a naval confrontation in the Gulf of Tonkin off the coast of North Vietnam, which led to the United States engaging more directly in the Vietnam War. On 2 August 1964 there was a clash between a destroyer of the United States Navy that was collecting signals intelligence close to North Vietnamese waters, and three North Vietnamese naval vessels. On the night of 4 August, two US destroyers reported they were attacked by North Vietnamese vessels and that they were returning fire. Later investigation revealed that the 4 August attack did not happen; no North Vietnamese vessels had been present. Shortly after the events, the National Security Agency, an agency of the US Defense Department, deliberately skewed intelligence to create the impression that an attack had been carried out.

On the night of 30 July, South Vietnamese commandos raided a North Vietnamese radar station on the island of Hòn Mê in the Gulf of Tonkin. The next day the destroyer USS Maddox commanded by Commander Herbert L. Ogier began patrolling near the North Vietnamese coast. On 2 August, the Maddox, while performing a signals intelligence patrol as part of DESOTO operations, near one of the islands that had been shelled two nights before, was approached by three North Vietnamese Navy torpedo boats of the 135th Torpedo Squadron. Maddox fired warning shots and the North Vietnamese boats attacked with torpedoes and machine gun fire. In the ensuing engagement, one US aircraft (which had been launched from aircraft carrier USS Ticonderoga) was damaged, three North Vietnamese torpedo boats were damaged, and four North Vietnamese sailors were killed, with six more wounded. There were no US casualties. Maddox was "unscathed except for a single bullet hole from a [North] Vietnamese machine gun round".

On 3 August, destroyer USS Turner Joy joined Maddox and the two destroyers continued the DESOTO mission. On the evening of 4 August, the ships opened fire on radar returns that had been preceded by communications intercepts, which US forces claimed meant an attack was imminent. The commodore of the Maddox task force, Captain John Herrick, reported that the ships were being attacked by North Vietnamese boats when, in fact, there were no North Vietnamese boats in the area. While Herrick soon reported doubts regarding the task force's initial perceptions of the attack, the Johnson administration relied on the wrongly interpreted National Security Agency communications intercepts to conclude that the attack was real.

While doubts regarding the perceived second attack have been expressed since 1964, it was not until years later that it was shown conclusively never to have happened. In the 2003 documentary The Fog of War, the former United States secretary of defense, Robert S. McNamara, admitted that there was no attack on 4 August. In 1995, McNamara met with former North Vietnamese Army General Võ Nguyên Giáp to ask what happened on 4 August 1964. "Absolutely nothing", Giáp replied. Giáp confirmed that the attack had been imaginary. In 2005, an internal National Security Agency historical study was declassified; it concluded that Maddox had engaged the North Vietnamese Navy on 2 August, but that the incident of 4 August was based on bad naval intelligence and misrepresentations of North Vietnamese communications. The official US government claim is that it was based mostly on erroneously interpreted communications intercepts.

The outcome of the incident was the passage by US Congress of the Gulf of Tonkin Resolution, which granted US president Lyndon B. Johnson the authority to assist any Southeast Asian country whose government was considered to be jeopardized by communist aggression. The resolution served as Johnson's legal justification for deploying US conventional forces to South Vietnam and the commencement of open warfare against North Vietnam in early 1965.