An invasion is a military offensive consisting of all, or large parts of the armed forces of one geopolitical entity aggressively entering territory controlled by another such entity, generally with the objective of either conquering, liberating or re-establishing control or authority over a territory, forcing the partition of a country, altering the established government or gaining concessions from said government, or a combination thereof. An invasion can be the cause of a war, be a part of a larger strategy to end a war, or it can constitute an entire war in itself.