Misawa Air Base (三沢飛行場, Misawa Hikōjō) (IATA: MSJ, ICAO: RJSM) is a U.S. military facility located 3 NM (5.6 km; 3.5 mi) northeast of the railway station in Misawa, 3 mi (4.8 km) west of the Pacific Ocean, 10 mi (16 km) northeast of Towada, 18 mi (29 km) northwest of Hachinohe, and 425 mi (684 km) north of Tokyo, in Aomori Prefecture, in the Tōhoku region in the northern part of the island of Honshū of Japan. It is a Pacific Air Forces (PACAF) facility with the 35th Fighter Wing (35 FW) as its host wing.
Misawa is the only combined, joint service installation in the western Pacific. It houses three U.S. military services (Army, Navy, and Air Force), as well as the Japan Self-Defense Forces. The base is home to 5,200 US military personnel, as well as 350 US civilian employees and 900 Japanese national employees.
The Misawa Passive Radio Frequency space surveillance site was used for tracking satellites using the signals they transmit. It also provides coverage of geosynchronous satellites using the Deep Space Tracking System (DSTS) but has been dismantled around 2002. The Misawa Security Operations Center (MSOC), located in the northwestern part of the Air Base, is believed to be one of the largest ECHELON ground stations.
An military airbase (sometimes referred to as a military airfield, military airport, air force station, air force base or short airbase) is an aerodrome used by a military force for the operation of military aircraft.
An airbase typically has some facilities similar to a civilian airport—for example air traffic control and firefighting. Some military aerodromes have passenger facilities; for example RAF Brize Norton in England has a terminal used by passengers for the Royal Air Force's flights by TriStar to the Falkland Islands. A number of military airbases also have a civil enclave for commercial passenger flights, e.g. Beijing Nanyuan Airport (China), Ibaraki Airport (Japan), Burlington International Airport (USA).
Some airbases have revetments, hardened aircraft shelters, or even underground hangars, to protect aircraft from enemy attack. Combat aircraft require storage of aircraft ordnance. An airbase may be defended by anti-aircraft weapons and force protection troops.