The correct answer is imperialism
The term imperialism is used to refer to the practices of politics in which a nation sought to promote territorial, economic and / or cultural expansion over another nation. The use of the word imperialism can occur in current contexts, for example, when one country decides to intervene militarily in another.
The Vietnam war was in favour of the Northern revolutionary forces. Just after the war, a peace treaty was signed which allows a government to be initiated in the Southern Vietnam, to find out that it has become a puppet government of the North, therefore, Vietnam remained to be a communist state.
