Gulf of Tonkin

The Gulf of Tonkin (, ; formerly known as or during the ROC period) is a gulf at the northwestern portion of the South China Sea, located off the coasts of Tonkin (northern Vietnam) and South China. It is defined in the west and northwest by the northern coastline of Vietnam down to the Hòn La Island, in the north by China's Guangxi Zhuang Autonomous Region, and to the east by the Leizhou Peninsula and Hainan Island.
Etymology.
The bay's Vietnamese and Chinese names – and , respectively – both mean "Northern Bay". "Bắc Bộ" is the native Vietnamese name of Tonkin. The name "Tonkin", written "" in Hán-Nôm characters and in the Vietnamese alphabet, means "eastern capital", and is the former toponym for Hanoi, the present capital of Vietnam. It should not to be confused with Tokyo, which is also written "" and also means "eastern capital". During Vietnam's French colonial era, the northern region was called "Tonkin".
1964 incident.
On 2 August 1964, United States President Lyndon B. Johnson falsely claimed that North Vietnamese forces had twice attacked American destroyers in the Gulf of Tonkin.</ref>"LBJ tape 'confirms Vietnam war error'." Martin Fletcher. "The Times". 7 November 2001.</ref> Known today as the Gulf of Tonkin Incident, this event spawned the Gulf of Tonkin Resolution of 7 August 1964, ultimately leading to open war between North Vietnam and the United States. It furthermore foreshadowed the major escalation of the Vietnam War in South Vietnam, which began with the landing of US regular combat troops at Da Nang in 1965.