Why was West Berlin an enclave inside East Germany?

West Berlin became an enclave inside East Germany due to the post-World War II occupation agreements made by the Allied powers.12

Following Germany's surrender in 1945, the country was divided into four occupation zones controlled by the United States, the United Kingdom, France, and the Soviet Union. Although Berlin was located deep within the Soviet zone of occupation, the city itself was also partitioned into four sectors under joint four-power authority.123

When the Western Allies and the Soviet Union failed to reach a consensus on the future of Germany, the occupation zones evolved into two separate states in 1949: the Federal Republic of Germany (West Germany) and the German Democratic Republic (East Germany). Because West Berlin remained under the administration of the Western Allies, it became an isolated enclave surrounded by the territory of East Germany. This status made the city a focal point of Cold War tensions, eventually leading to the construction of the Berlin Wall in 1961.1234