Gulf of Tonkin is the sea area between Vietnam and China. Hai Phong Port in the Gulf of Tonkin was the biggest port in North Vietnam at the time. Via Hai Phong, North Vietnam received aids from outside during the war. Historically a lot of conflicts in Vietnam started in Hai Phong thanks to its strategic location.

After the division of Vietnam into Democratic Republic of Vietnam (North Vietnam) and Republic of Vietnam (South Vietnam), there were covert operations against North Vietnam by the CIA and later by the US Defense Department. The Gulf of Tonkin and Hai Phong Harbor were among the targets of those operations, in which US-trained South Vietnamese maritime commandos with fast boats and under direct command of the US Admiral conducted different attacks on different targets in the area. It happened that the Tonkin Gulf Incident occurred “coincidentally” at the same time with raids by South Vietnamese Commandos in the area.

On 2nd August 1964, an  American Destroyer USS Maddox claimed to have been attacked by North Vietnamese torpedo boats while it was in international waters off the coast of North Vietnam. Maddox returned fire and retired to South Vietnam and was joined by another destroyer, Turner Joy. On 4th August 1964, the two destroyers launched another patrol off the coast of North Vietnam and were believed that there were indications via radar and radio signals that they were attacked by North Vietnamese Navy.

On 4th August 1964, Lyndon Johnson, who was up for the presidential election the same year, went on television and denounced the incidents as "open aggression on the high seas" by the North Vietnamese and ordered retaliatory air strikes on North Vietnamese Naval bases. Defense Secretary Robert  S. McNamara, in his testimony before Congress on August 6th, characterized the attacks as “unprovoked” and denied that the US Navy had been involved in military operations in the area along with the South Vietnamese.

On August 7th 1964, Congress passed a joint resolution called the “Gulf of Tonkin Resolution” allowing Lyndon Johnson the authority to conduct any military operations in South East Asia without formal declaration of war by Congress. Obtaining the necessary “blank check”, Lyndon Johnson escalated the war including committing more US troops in Vietnam and the saturation bombings of North Vietnam between 1964 – 1972.

By 1967, the US military involvements in Vietnam had proved to be more and more costly and anti-war movements had started mounting; a movement to repeal the resolution also began. Investigations into the Tonkin Gulf Incidents revealed that Maddox had been on an electronic intelligence collection mission while the first attack occurred and whether the second attack occurred or not was still in question...