Invasion

An invasion is a military action consisting of armed forces of one geopolitical entity entering territory controlled by another such entity, generally with the objective of either conquering territory, altering the established government, or a combination thereof. An invasion can be the cause of a war, it can be used as a part of a larger strategy to end a war, or it can constitute an entire war in itself.

The term usually denotes a strategic endeavor of substantial magnitude; because the goals of an invasion are usually large-scale and long-term, a sizeable force is needed to hold territory, and protect the interests of the invading entity. Smaller-scale, tactical cross-border actions, such as skirmishes, sorties, raids, infiltrations or guerrilla warfare, are not generally considered invasions. Because an invasion is, by definition, an attack from outside forces, rebellions, civil wars, coups d'état, and internal acts of democide or other acts of oppression, are not considered invasions.