In 1970, President Nixon announced the gradual withdraw from Vietnam called Vietnamization; giving Vietnam back to the Vietnamese.  Fighting continued for three more years and in 1973, the Treaty of Paris was signed in France between the US and North Vietnam.  The treaty stated:

1. The US would withdraw all forces from Vietnam.

2. Vietnam would remain split at the 17th parallel

Two years later, in 1975, North Vietnamese forces invaded the South and conquered the country.  President Ford ordered all Americans with leave Vietnam and it became a communist nation.