By the end of the 19th century, the region now occupied by Vietnam, Cambodia and Laos as under French colonial rule. During World War II, French Indochina was occupied by Japanese forces. After the Japanese surrender, the French hoped to regain control over the territory, but opposition by local ethnic and political interests, the Soviet Union and China resulted in the proclamation of competing governments by 1954. Communist backed forces gained the upper hand in the northern sector of Vietnam while anti-Communist factors claimed control of the South. Beginning that year, the United States gradually increased its involvement in the conflict. Following a massive escalation in late 1964, there were more than 500,000 American troops in Vietnam. The US was allied with the anti-Communist government of the Republic of Vietnam (South Vietnam) against the Democratic Republic of Vietnam (North Vietnam) and the southern based National Liberation Front (Viet Cong). American involvement ceased following the signing of the Vietnam Peace Pact in January 1973, but offensive action by Communist forces resumed soon thereafter. The South Vietnamese capital of Saigon fell in April 1975, leading to a Communist takeover of the entire country. Vietnam was reunified under a Communist government in July 1976.