Johnston Island Air Force Base  Johnston Island Air Force Base is a former United States Air Force base on the Johnston Atoll in the United States Minor Outlying Islands, in the Pacific Ocean several hundred kilometers southwest of Hawaii. After its closure, it briefly operated as Johnston Atoll Airport, until its closure in 2005. In 1935 personnel from the US Navy's Patrol Wing Two carried out some minor construction to develop the atoll for seaplane operation. They erected some buildings and a boat landing on Sand Island and blasted coral to clear a seaplane landing. In November 1939 further work was commenced on Sand Island by civilian contractors to allow the operation of one squadron of patrol planes with tender support. Part of the lagoon was dredged and the excavated material was used to make a plane parking area connected by a causeway to Sand Island. Three seaplane landings were cleared, one by and two cross-landings each by and dredged to a depth of . On Sand Island barracks were built for 400 men, a messhall, underground hospital, radio station, water tanks and a steel control tower. In February 1941 Johnston Atoll was designated as a Naval Defensive Sea Area and Airspace Reservation. In September 1941 construction of an airfield on Johnston Island commenced. A by runway was built together with two 400-man barracks, two messhalls, a cold-storage building, an underground hospital, a fresh-water plant, shop buildings and fuel storage. The base was complete by 7 December 1941. On 15 December 1941 the atoll was shelled by a Japanese submarine outside the reef, several buildings were hit, but no personnel were injured. In July 1942 the civilian contractors at the atoll were replaced by 500 Seebees from the 5th and 10th Naval Construction Battalions, who expanded the fuel storage and water production at the base and built additional facilities. The 5th Battalion departed in January 1943. In December 1943 the 99th Naval Construction Battalion arrived at the atoll and proceeded to lengthen the runway to and add an additional of parking to the seaplane base. US Navy and Marine units based at Johnston included:   US Navy and Marine units based at Johnston included: