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Exercise Space Flag is a United States Space Force (USSF) exercise dedicated to providing tactical space units with advanced training in a contested, degraded, and operationally-limited (CDO) environment. The intent of Space Flag is to provide space forces with realistic, threat-based training to enhance their ability to analyze and respond to current and future threats within a broader warfighting context. Space Flag is the USSF's sole large-force employment exercise focused on gaining and maintaining space superiority and was modeled after the U.S. Air Force's Red Flag Exercise.^[1][2]

With the activation of Space Training and Readiness Delta Provisional (STAR Delta) on 24 July 2020, the unit responsible for Space Flag has been re-organized under STAR Delta^[3] and temporarily re-designated STAR Delta, Operating Location-Alpha (OL-A). STAR Delta, OL-A was previously known as Distributed Mission Operations Center-Space (DMOC-S)^[3] or the 705th Combat Training Squadron (CTS), OL-A^[4] and is located at Schriever Air Force Base, Colorado.

The first Space Flag was held in April 2017.^[5][6] For the first two calendar years—2017 and 2018—Space Flag occurred twice per year. Starting in 2019, Space Flag increased to three times per year,^[7] with one iteration as a coalition event. Space Flag 19-3 in August 2019, was the first event to include coalition partners from Australia, Canada, Great Britain, and the United States.^[8][9]

The 527th Space Aggressor Squadron and 26th Space Aggressor Squadron operate the red cell and provide Opposing force functions or OPFOR for Space Flag.^[6]

Space Flag was loosely referenced in episode 5 of the Netflix series Space Force (TV series).