The primary mission of the 12th SWS is to provide critical, real-time missile warning, defense and space surveillance to the President of the United States, Secretary of Defense, the Joint Chiefs of Staff, NORAD, and unified commands by operating a phased-array radar—which continuously provides warning of Submarine-launched ballistic missile (SLBM) and Intercontinental ballistic missile attacks against North America—and detect, track, and identify earth-orbiting objects in support of USSTRATCOM’s space control mission, thus "knitting a blanket of freedom".
To accomplish its mission, the squadron operates the solid-state phased-array radar located at the Ballistic Missile Early Warning System (BMEWS), Site I. The BMEWS site is located approximately 11 miles northwest of Thule AB 76°34′08″N68°19′05″W / 76.569°N 68.318°W / 76.569; -68.318. It provides early warning detection of intercontinental ballistic missile (ICBM) launches from the Russian land mass and submarine-launched ballistic missile (SLBM) launches from the North Atlantic and Arctic Oceans against North America. Additionally, BMEWS keeps track of polar orbiting satellites. The operational crews report through the Missile Warning Center to the NORAD/USNORTHCOM Center.
The Operation Support Flight provides direct operational support to the missile warning crews. The flight's Operations Training Section (DOUT) provides all crew force initial, recurring, and supplemental training. Other flight responsibilities include hardware and software development, operational test and evaluation (DOV), and crew force management (DOU).
With the development of ICBM and SLBM technologies, the mission to monitor aircraft coming over the horizon from the Soviet Union was transferred to other units, and the 931st AC&WS at Thule AB was inactivated.