invasion

An invasion is the entry of an armed force into another country or its territory with the aim of defeating its government, occupying land, or altering the political order. It is typically a large-scale operation that may involve land, air, and sea elements, and it is often followed by occupation or administration of the occupied area. Invasions differ from smaller incursions, raids, or border violations in their scale, intent, and duration, and they are usually aimed at subjugation and control of territory.

Legal and normative context: Modern international law prohibits the threat or use of force against the territorial integrity of states, with limited exceptions such as self-defense or actions authorized by the UN Security Council. Whether an invasion is legal depends on these criteria and subsequent international response. Invasions can lead to occupation, attempts at annexation, or regime change, and they frequently raise questions about sovereignty, legitimacy, and responsibility for civilians.

Tactics and consequences: Invasions commonly involve rapid advances, seizure of strategic infrastructure, and attempts to establish governance in occupied areas. They can cause humanitarian crises, mass displacement, economic disruption, and long-term political instability. International responses may include sanctions, diplomatic condemnation, peacekeeping, or, in some cases, collective security actions.

Notable examples: Historical invasions include the invasion of Poland in 1939, which contributed to the start of World War II; the Norman invasion of England in 1066; the 2003 invasion of Iraq; and more recent cases such as the 2014 and 2022 Russian actions in Ukraine. These events illustrate invasion as a mechanism for territorial change and political realignment, often with enduring regional consequences.