In the first stage, US negotiated a peace treaty with the nationalist Vietnamese. It was clear that the US had failed to achieve its objectives. The Paris Accord provided them a way out of the war.
In the second stage, the South Vietnamese regime was engaged in fighting with the National Liberation Front (NLF).
The NLF occupied the presidential palace in Saigon on 30 April 1975. North Vietnam and South Vietnam were unified into a single nation.
