After World War I, the British built the large Singapore Naval Base as part of the defensive Singapore strategy. First announced in 1921, the construction of the base went at a slow pace until the Japanese invasion of Manchuria in 1931. Costing $60 million and not fully completed in 1938, it was the largest dry dock in the world, the third-largest floating dock, and had enough fuel tanks to support the entire British navy for six months. The base was defended by heavy naval guns stationed at Fort Siloso, Fort Canning and Labrador Park, as well as a Royal Air Force airfield at Tengah Air Base. Winston Churchill called Singapore the "Gibraltar of the East", and military discussions often referred to the base as just "East of Suez".