21st Operations Group
The 21st Operations Group is a United States Space Force operational unit responsible for space-domain awareness, missile warning, space surveillance, and related defense missions.
Last updated August 26, 2026
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Overview
The 21st Operations Group is a United States military operational organization whose lineage extends from World War II bomber and fighter formations to contemporary space-domain awareness and missile-warning missions. It was first established on 1 February 1942 as the 21st Bombardment Group at Bowman Field, Kentucky. During the American Theater of World War II, the group trained bomber crews and later operated B-25 Mitchell and B-26 Marauder aircraft on anti-submarine patrols in the Caribbean. That formation was inactivated in October 1943. A successor formation, the 21st Fighter Group, was activated in Hawaii in 1944. It initially flew P-39 Airacobras, later transitioned to P-38 Lightnings and P-51 Mustangs, and provided air defense over the Hawaiian Islands. In 1945, the group deployed to Iwo Jima, where its personnel participated in ground fighting during the island's capture and subsequently conducted close-air-support missions and long-range fighter escorts for B-29 bombers attacking Japan. The unit's escort mission to the Nakajima Aircraft Company near Tokyo on 7 April 1945 was an important milestone in Pacific air operations, and the group received a Distinguished Unit Citation for its combat record. After World War II, the formation was reactivated in 1953 as the 21st Fighter-Bomber Group. It operated F-51 Mustangs and then F-86 Sabres, took part in Arctic, tactical-deployment, gunnery, and NATO exercises, and deployed to Chambley Air Base in France in support of NATO during the Cold War. The group was inactivated in 1958 and was later redesignated the 21st Tactical Fighter Group in 1985 without being immediately activated. The organization was briefly activated as the 21st Operations Group at Elmendorf Air Force Base, Alaska, in September 1991. Its aircraft units operated F-15C and F-15E fighters in support of Alaskan air defense and the North American Aerospace Defense Command. It was inactivated in December of the same year after an Air Force reorganization at Elmendorf. The group returned to active service on 15 May 1992 under the 21st Space Wing at Peterson Air Force Base. In this era, its responsibilities centered on missile warning, space surveillance, and space control. It oversaw or supported a broad network of early-warning radars, optical systems, passive sensors, and space-surveillance facilities distributed across the United States and overseas locations. These included Defense Support Program missile-warning operations, Ballistic Missile Early Warning System radars, PAVE PAWS installations, the AN/FPQ-16 PARCS radar, the AN/FPS-85 space-surveillance radar, GEODSS optical sites, and other surveillance systems. The organization was redesignated Space Delta 2 on 24 July 2020 and transferred from the United States Air Force to the United States Space Force on 21 October 2020. On 31 October 2024, it was redesignated Mission Delta 2. In its current form, Mission Delta 2 tracks and monitors human-made objects from low Earth orbit through geosynchronous orbit and into deep space. It also cooperates with the National Oceanic and Atmospheric Administration on weather-satellite observation supporting the U.S. armed forces. The modern formation includes the 15th Space Surveillance Squadron, 18th Space Defense Squadron, 19th Space Defense Squadron, and 20th Space Surveillance Squadron, and has gained sustainment, organic cyber-defense, and intelligence responsibilities.
History
The unit's lineage began during the rapid expansion of the United States Army Air Forces in World War II. The 21st Bombardment Group was activated at Bowman Field, Kentucky, on 1 February 1942. It moved through several training bases in the southeastern United States and was assigned to bomber-command organizations before converting from B-25 Mitchells to B-26 Marauders at MacDill Field, Florida. Its wartime role included operational training and anti-submarine patrols in the Caribbean. The group was inactivated on 10 October 1943. A fighter formation carrying the 21st designation was activated in Hawaii in 1944. The 21st Fighter Group included the 46th, 72nd, and 531st Fighter Squadrons and was initially equipped with P-39Q Airacobras. It provided air defense for the Hawaiian Islands, transitioned to P-38J/L Lightnings, and then adopted P-51 Mustangs. In early 1945, the group moved to Iwo Jima. Its personnel fought Japanese ground forces during the early fighting on the island, after which the group provided close air support and fighter protection for bomber operations against Japan. On 7 April 1945, its Mustangs escorted B-29 bombers to targets near Tokyo. The group flew its final combat mission over Japan on 14 August 1945 and was eventually inactivated at Guam in October 1946. The formation was reactivated in 1953 as the 21st Fighter-Bomber Group under the 21st Fighter-Bomber Wing. It transitioned from F-51s to F-86F Sabres and participated in Arctic warfare training, overseas deployment exercises, tactical gunnery events, and NATO activities. In 1954, the group and its parent wing were selected for deployment to France. The group was formally based at Chambley Air Base from December 1954, although infrastructure improvements meant that its jet operations initially used other French airfields. Its Cold War mission involved close-air-support preparation and defense of NATO territory. The group was inactivated with its wing in February 1958. In 1985, the inactive organization was redesignated the 21st Tactical Fighter Group. It was activated as the 21st Operations Group at Elmendorf Air Force Base on 25 September 1991, operating F-15C and F-15E fighter squadrons for Alaskan air defense and NORAD support. A restructuring of the Elmendorf wing arrangement led to its inactivation on 19 December 1991. The group was reactivated on 15 May 1992 at Peterson Air Force Base under the 21st Space Wing. It assumed space and missile-warning responsibilities previously associated with the 1st Space Wing and managed a distributed architecture of orbital surveillance and early-warning systems. Its responsibilities included Defense Support Program missile-warning satellites, BMEWS radars in Alaska, Greenland, and the United Kingdom, PAVE PAWS installations in the United States, the PARCS radar, and space-surveillance systems such as the AN/FPS-85 and GEODSS. Overseas sensors and detachments extended the network to Turkey, Japan, Diego Garcia, Hawaii, South Korea, the United Kingdom, and other locations. Some sites and squadrons were later retired or transferred as missions and force structures changed. The formation became Space Delta 2 on 24 July 2020 and entered the United States Space Force on 21 October 2020. On 31 October 2024, it became Mission Delta 2 and received a broader mission set including sustainment, organic cyber defense, and intelligence. Its present role is centered on space-domain awareness: tracking and monitoring human-made objects across a wide range of orbital regimes and farther into deep space, while also supporting military weather-satellite observation in cooperation with NOAA.
- 2024
Redesignation as Mission Delta 2
[1]On 31 October, the organization became Mission Delta 2 and added sustainment, cyber-defense, and intelligence responsibilities to its space-domain mission.
- 2020
Redesignation as Space Delta 2
[1]The organization was redesignated Space Delta 2 on 24 July and transferred to the United States Space Force on 21 October.
- 1992
Return as a space operations organization
[1]The group was reactivated under the 21st Space Wing at Peterson Air Force Base and assumed missile-warning, space-surveillance, and space-control responsibilities.
- 1991
Brief activation for Alaskan air defense
[1]The 21st Operations Group was activated at Elmendorf Air Force Base with F-15C and F-15E fighter units, but was inactivated later that year.
- 1954
NATO deployment to France
[1]The group deployed to Chambley Air Base in France as part of NATO's Cold War defense posture.
- 1953
Reactivation as the 21st Fighter-Bomber Group
[1]The formation returned to active service at George Air Force Base and transitioned from piston-engine fighters to F-86 Sabre jets.
- 1945
Iwo Jima and bomber-escort operations
[1]The fighter group deployed to Iwo Jima, provided close air support, and began long-range P-51 escort missions for B-29 raids over Japan.
- 1944
Activation of the 21st Fighter Group
[1]A successor fighter formation was activated in Hawaii and assigned air-defense duties, later transitioning through several fighter types.
- 1943
Inactivation of the World War II bomber formation
[1]The 21st Bombardment Group was inactivated on 10 October after conducting training and anti-submarine patrol duties.
- 1942
Activation as the 21st Bombardment Group
[1]The 21st Bombardment Group was activated on 1 February at Bowman Field, Kentucky, beginning the organizational lineage that later led to the modern space unit.
Products and positioning
A United States military space organization focused on persistent detection, tracking, characterization, and defense-related assessment of objects and activity in the space domain.
Military space operations
Space-domain awareness
The organization's principal contemporary capability is the detection, tracking, and monitoring of human-made objects across orbital regimes ranging from low Earth orbit to geosynchronous orbit and beyond. It combines data from radar, optical, and passive surveillance systems to support characterization of the space environment and military decision-making.
Early-warning defense
Missile-warning operations
During its Air Force space-operations period, the group operated or supported satellite and ground-based systems designed to detect missile launches and provide early warning. Relevant systems included Defense Support Program assets, BMEWS radars, PAVE PAWS installations, and the PARCS radar.
Sensor network
Global space-surveillance sensors
The lineage includes operations involving the AN/FPS-85 radar, GEODSS optical facilities, passive radar systems, and other sensors located in the United States and overseas. These systems supported observation of satellites, orbital debris, launches, and other space activity.
Marketing campaigns
- 1992Missile warning and space surveillance network operations
United States · Europe · Asia-Pacific · Middle East
Under the 21st Space Wing, the group operated and coordinated a geographically distributed network of missile-warning radars, satellite-warning systems, optical telescopes, and space-surveillance sensors.
Outcome. The mission evolved through organizational transfers, sensor upgrades, and the creation of the United States Space Force.
- 1954NATO Cold War defense deployment
France · Europe · North Atlantic Treaty Organization
The fighter-bomber group deployed F-86 aircraft and personnel to France, conducting tactical proficiency, close-air-support, and NATO-related training.
Outcome. The formation remained part of the NATO defense posture until its inactivation in 1958.
- 1945Iwo Jima and Japan bomber escort operations
Iwo Jima · Japan · Pacific Theater
The 21st Fighter Group supported the capture of Iwo Jima, conducted close air support, and escorted B-29 bombers on long-range missions over Japan.
Outcome. The group received a Distinguished Unit Citation for its World War II combat performance.
- 1942American Theater anti-submarine patrols
Caribbean Sea · United States
The 21st Bombardment Group used B-26 Marauders for anti-submarine patrols in the Caribbean during World War II.
Outcome. The bomber group was inactivated in October 1943.
Brand decisions
2024
Expansion and redesignation as Mission Delta 2StrategyBackground
The Space Force revised the organization's designation and mission structure to reflect a broader operational role.
Action taken
On 31 October 2024, Space Delta 2 was redesignated Mission Delta 2 and gained sustainment, organic cyber-defense, and intelligence responsibilities.
Aftermath
The unit's remit expanded beyond sensor operations to include additional support functions for space-domain awareness and defense.
2020
Transfer from the Air Force to the Space ForceStrategyBackground
The creation of the United States Space Force required the reassignment of eligible space organizations from the Air Force.
Action taken
The organization was redesignated Space Delta 2 and transferred to the Space Force in October 2020.
Aftermath
Its space-surveillance and related defense missions continued under the new service structure.
Sources2 sources
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