Military advisors first arrived in Vietnam in 1950. America started sending troops into Vietnam as early as 1960, but they took no military action until 1965. The United States was actively (militarily) involved in the Vietnam War from 1965 to 1975.

The Vietnam War 'era' was 1961 to 1975.

No. The United States had full diplomatic relations with the Republic of Vietnam (colloquially called South Vietnam) from 1954-1975 when that country was conquered by the Socialist Republic of Vietnam (colloquially called North Vietnam or just Vietnam today) in 1975 at the close of the Vietnam War (the Vietnamese call it the American War).

The United States established full diplomatic relations with the Socialist Republic of Vietnam in 1995 as Vietnam embraced a market economy and was beginning to reach out to other ASEAN nations.

US Military personnel were in Vietnam from 1955 thru 1975.

The Vietnam War happened in the 1960's and throughout the 60's. The Vietnam War is considered to be one of the most pointless wars in US history.