An invasion is an act of forcefully entering another country's territory with military forces without consent. The purpose of an invasion can be conquest, annexation, regime change, or strategic objectives.
Related terms
Occupation: Occupation occurs when a foreign military force establishes control over another nation's territory for an extended period either temporarily (during war) or permanently (through annexation).
Aggression: Aggression refers to any unjustified use of force by one state against another beyond the boundaries allowed by international law. It includes acts like invasions and attacks.
Sovereignty: Sovereignty is the supreme authority of a state within its own borders. Invasions challenge the sovereignty of the invaded country as it loses control over its territory temporarily or permanently.