Following the fall of the Shah of Iran and the Iran Hostage Crisis in 1979–1980, the West became concerned with ensuring the flow of oil from the Persian Gulf through the Strait of Hormuz, and the United States received permission for a $400-million expansion of the military facilities on Diego Garcia consisting of two parallel  runways, expansive parking aprons for heavy bombers, 20 new anchorages in the lagoon, a deep-water pier, port facilities for the largest naval vessels in the American or British fleet, aircraft hangars, maintenance buildings and an air terminal, a  fuel storage area, and billeting and messing facilities for thousands of sailors and support personnel.