United States Air Force

The United States Air Force was a branch of the armed forces of the United States of America, an Earth nation-state, during the 20th century. Its predecessor was the United States Army Air Corps. The Air Force was chiefly responsible for deploying military aircraft, although the Navy operated aircraft carriers. The Air Force also maintained a fleet of intercontinental ballistic missiles, as part of the Earth Cold War and later World War III. Zefram Cochrane eventually converted one such missile into the prototype warp ship Phoenix. 

In 1953, Roy Ritterhouse drew an illustration for Incredible Tales magazine, depicting a space station that was operated by the US Air Force. The illustration later became part of the "Deep Space Nine" novella. 

In 1969, the Air Force detected the USS Enterprise (NCC-1701), after it had arrived through an accidental time warp from 2267. Alarmed, Air Defense Command ordered the US 498th Airbase Group to scramble an F-104 Starfighter. Its pilot, Captain John Christopher, attempted to intercept the Enterprise. In one version of history, his plane was destroyed and he was taken aboard the ship. In the historical timeline "recreated" by Spock's slingshot method of returning to the future, the ship vanished before Christopher could reach it, and he returned to his base, unaware of what he had seen. 

When the USS Voyager was accidentally transported to 1996, and flew through Earth's atmosphere over Los Angeles, the United States military took the incident quite seriously. Captain Janeway feared that if the ship risked another pass through the lower atmosphere, it risked being intercepted by the Air Force.