Diem’s overthrow had been attempted in 1960 and 1962, respectively. He had held onto power both times, but in 1963, things got harder for him. On June 11, a severe setback was delivered to his government by an incident. Thich Quang Duc, a Buddhist monk, burnt himself to death at a public intersection in Saigon. He was speaking out against Diem’s persecution towards Buddhists. His passing was documented on camera and broadcast all over the world. Thich Quang Duc’s death, according to Diem’s communist adversaries, was a protest against the war.

This was cited by them as another proof that Diem did not enjoy popular support in Vietnam. The US was now concerned that Diem’s dictatorship was harming its anticommunist campaign in Southeast Asia. Diem was overthrown in a military coup in November 1963. On November 2nd, Diem and his brother Ngo Dinh Nhu were apprehended and killed in the trunk of an armored personnel carrier. The coup leaders thought they had the backing of the US government.
Vietnam did not become more stable as a result of Diem’s murder. The generals fought with one another and elevated their own men to powerful positions over the course of the following few years. There could never be a stable government. In South Vietnam, some stability was finally achieved by General Nguyen Van Thieu in 1965.
The Viet Cong benefited from southern unrest. US President Johnson made a decision to take action in 1965. He did not consider the battle to be a civil war and believed that other Southeast Asian nations without US help would be overthrown by communists. The US chose to send soldiers to South Vietnam and started attacking the North with its air force.