annexation

Annexation is the formal incorporation of territory into a state or political entity. It can result from voluntary agreement or from unilateral action. In international law, annexation refers to the legal extension of a state's sovereignty over a territory that was previously outside its borders; its legitimacy is often contested.

There are two broad forms. Voluntary annexation occurs when the territory consents or is admitted by treaty or referendum, and the change is recognized by other states. Unilateral annexation occurs when a state proclaims incorporation after conquest, occupation, or unilateral assertion of sovereignty, without mutual consent. A related concept is de facto annexation, where a state exercises effective control and administration without formal legal title.

Legal status and international response: Since World War II, territorial acquisitions by force are generally condemned under the UN Charter, and many states do not recognize unilateral annexations. Recognition is political and varies by state, often influenced by principles of territorial integrity and the legitimacy of the procedures used. Domestic law may apply to governance and citizenship in the annexed territory, but such changes do not guarantee international recognition.

Examples and implications: The United States’ 1845 annexation of Texas and the 1898 annexation of Hawaii are often described as voluntary expansions within a federation. The 1938 Anschluss of Austria by Germany is widely regarded as illegal under international law. The 2014 annexation of Crimea by Russia followed a disputed referendum and was not recognized by most members of the international community. Annexation can alter sovereignty, governance, and citizenship, and frequently shapes international relations and conflict dynamics.