National security matters are authorized to be classified.
The Korean war
Presuming you mean the government supported by the US: The Republic of South Vietnam.
Because Vietnam's government was communist
The US objective was to bolster the government of South Vietnam and keep it from being taken over by North Vietnam. The US spent much money and human life trying to achieve this goal, but in 1975 South Vietnam collapsed under a North Vietnamese invasion.
the Us and Vietnam government
Had to, US troops=US government.
Isolationists made little effort in the early (Post Dien Bin Phu) days. It was the anti war protests against the war and the draft that fought against the Vietnam War.
Mainly the Vietnam War ?
A homefront that seriously distrusts its government.
The Bungling US Government in Washington D. c.
The U.S. feared that Vietnam would vote for a communist government.
Discontent with the government.