The correct answer is: "imperialism".
Direct interventions on foreign countries, such as the presence of military troops, exemplify the imperalist foreign policy approach of the US.
New forms of imperalism differ from the traditional colonial approach. It is not necessary that the US explicitly controls a territory by leading its institutions and goveremnt, it can do so by exercising its influence to determine the main political, economical and social decisions reached in a country. Military powers is one of the strategies that the US can use to impose its objectives on a foreign nation.