Vietnam War
From 1953 to 1956, the North Vietnamese government instituted agrarian reforms including "rent reduction" and "land reform", which resulted in significant political repression.[130] This included 13,500 to as many as 100,000 executions.[131][132] In the South, Diệm countered North Vietnamese subversion (including the assassination of over 450 South Vietnamese officials in 1956) by detaining tens of thousands of suspected communists in "political reeducation centres".[133][134] This programme incarcerated many non-communists, but was successful at curtailing communist activity in the country, if only for a time.[135] The North Vietnamese government claimed that 2,148 people were killed in the process by November 1957.[136] The pro-Hanoi Việt Cộng began a guerrilla campaign in South Vietnam in the late 1950s to overthrow Diệm's government.[137] From 1960, the Soviet Union and North Vietnam signed treaties providing for further Soviet military support.[138][139][140]
In 1963, Buddhist discontent with Diệm's Catholic regime erupted into mass demonstrations, leading to a violent government crackdown.[141] This led to the collapse of Diệm's relationship with the United States, and ultimately to a 1963 coup in which he and Nhu were assassinated.[142] The Diệm era was followed by more than a dozen successive military governments, before the pairing of Air Marshal Nguyễn Cao Kỳ and General Nguyễn Văn Thiệu took control in mid-1965.[143] Thiệu gradually outmaneuvered Kỳ and cemented his grip on power in fraudulent elections in 1967 and 1971.[144] During this political instability, the communists began to gain ground. To support South Vietnam's struggle against the communist insurgency, the United States used the 1964 Gulf of Tonkin incident as a pretext for increasing its contribution of military advisers.[145] US forces became involved in ground combat operations by 1965, and at their peak several years later, numbered more than 500,000.[146][147] The US also engaged in sustained aerial bombing. Meanwhile, China and the Soviet Union provided North Vietnam with significant material aid and 15,000 combat advisers.[138][139][148] Communist forces supplying the Việt Cộng carried supplies along the Hồ Chí Minh trail, which passed through Laos.[149]
The communists attacked South Vietnamese targets during the 1968 Tết Offensive. The campaign failed militarily, but shocked the American establishment and turned US public opinion against the war.[150] During the offensive, communist troops massacred over 3,000 civilians at Huế.[151][152] Facing an increasing casualty count, rising domestic opposition to the war, and growing international condemnation, the US began withdrawing from ground combat roles in the early 1970s. This also entailed an unsuccessful effort to strengthen and stabilise South Vietnam.[153] Following the Paris Peace Accords of 27 January 1973, all American combat troops were withdrawn by 29 March 1973.[154] In December 1974, North Vietnam captured the province of Phước Long and started a full-scale offensive, culminating in the fall of Saigon on 30 April 1975.[155] South Vietnam was ruled by a provisional government for almost eight years while under North Vietnamese military occupation.[156]