The Gulf of Tonkin is a body of water located off the northeastern coast of Vietnam. It is bordered by Vietnam to the west and the island of Hainan, China, to the north. The gulf is significant for its strategic location and has been a site of various naval activities throughout history. In August 1964, the Gulf of Tonkin Incident occurred, involving reported attacks on U.S. naval vessels by North Vietnamese forces. This event led to the passage of the Gulf of Tonkin Resolution, which escalated U.S. military involvement in the Vietnam War. The resolution allowed for increased military action without a formal declaration of war.