during US intervention in Vietnam they tried to pretend it was a war between two "independent" nations rather than a civil war

In The Green Berets, Western star John Wayne convinces sceptical news reporters that the Vietnam War is necessary and leads a team of Green Berets (US Special Forces) and Army of the Republic of Vietnam (ARVN) soldiers on a successful mission to capture a top North Vietnamese field commander.

During production of Green Berets, the DOD requested that the scriptwriter delete any mention of the soldiers entering Laos because it ‘raises sensitive questions.’ Presumably, these questions revolved around the fact that in the real world the US had been secretly bombing a neutral country for the past three years.

In a scene that explains the purpose of the war at the start of the film, Francis Tully, Speech Review Staff for the Department of State, also suggested that the scriptwriters insert the following language:

We do not see this as a civil war, and it is not. South Vietnam is an independent country, seeking to maintain its independence in the face of aggression by a neighbouring country. Our goal is to help the South Vietnamese retain their freedom, and to develop in the way they want to, without interference from outside the country.

These lines do not appear in the final film, but Tully’s suggestion indicates that he hoped to simplify the war in Vietnam in a way that Americans could support, and this simplification occurs though in the final version of the scene, as military leaders explain to reporters that the war boils down to stopping 'Communist domination of the world.'

from National Security Cinema by Alford & Secker