The Cheyenne Mountain Complex is a United States Space Force installation and defensive bunker located in unincorporated El Paso County, Colorado, next to the city of Colorado Springs,[2] at the Cheyenne Mountain Space Force Station,[a] which hosts the activities of several tenant units.

[12] The complex is the only underground Department of Defense facility certified to be able to sustain a high-altitude electromagnetic pulse (EMP).

Amenities include a medical facility, store, cafeteria,[12] and fitness centers inside and outside the mountain.

There is a network of blast valves with unique filters to capture airborne chemical, biological, radiological, and nuclear contaminants.

[12] There is a "massive" reservoir for diesel fuel and a "huge" battery bank with redundant power generators.

[18]: 5, 16  In the late 1950s, a plan was developed to construct a command and control center in a hardened facility as a Cold War defensive strategy against long-range Soviet bombers,[6] ballistic missiles, and a nuclear attack.

This underground facility was nicknamed "The Notch" (or formally as the 8th AF "Post-Attack Command and Control System Facility, Hadley") and was hardened to protect it from the effects of a nearby nuclear blast and designed so that the senior military staff could facilitate further military operations.

[21] Four years later, construction at Cheyenne Mountain was started to create a similar protection for the NORAD command post.

The electronics and communications system centralized and automated the instantaneous (one-millionth of a second) evaluation of aerospace surveillance data.

[31] NORAD had a series of warning and assessment systems that were not fully automated in the Cheyenne Mountain complex into the 1970s.

The new system was designed to centralize several databases, improve on-line display capabilities, and consolidate mission warning information processing and transmission.

For instance, a computer chip "went haywire" and issued false missile warnings, which raised the possibility that a nuclear war could be started accidentally, based upon incorrect data.

Staff analyzed the data and found that the warnings were erroneous, and the systems were updated to identify false alarms.

Gen. James V. Hartinger of the Air Force stated that "his primary responsibility is to provide Washington with what he calls 'timely, unambiguous, reliable warning' that a raid on North America has begun."

Following another failure in 1980, a bad computer chip was updated, and staff and commander processes were improved to better respond to warnings.

Testing of Granite Sentry nuclear detonation (NUDET) data processing system found it to be inadequate.

[42]: 2, 9–10 By 1992, the U.S. Space Command Space Surveillance Center (SSC) was the data analysis and tracking center for Baker-Nunn camera images[43] and Cheyenne Mountain was connected to the AN/URC-117 Ground Wave Emergency Network (GWEN)[42]: 16  communication site in Pueblo, Colorado.

By 1995, the AN/FPS-129 HAVE STARE (Globus II) radar in California had been upgraded to "relay data to Cheyenne Mountain",[44] and by October 1995 the 1st Command and Control Squadron (1CACS) in the bunker[where?]

[38]: 11  The portion of CCIC2S modernizing "attack warning systems within Cheyenne Mountain [was to] cost more than $700 million from fiscal years 2000 to 2006",[51] and the delayed CCIC2S upgrades for space surveillance were superseded[when?]

[54] On August 3, 2011, a ribbon cutting was held for the January 2010 – June 30, 2011, Missile Warning Center renovation funded by USSTRATCOM.

[6] Since 2002, the complex has been classed as Cheyenne Mountain Air Force Station and has been used in crew qualification training, while the former command function has been redesignated as the "NORAD and USNORTHCOM Alternate Command Center" since 2008 after all the original functions of the complex were removed to Peterson Air Force Base.

NORAD and USNORTHCOM now use just under 30% of the floor space within the complex and comprise approximately 5% of the daily population at Cheyenne Mountain.

[6] The Cheyenne Mountain Complex serves as NORAD and USNORTHCOM's Alternate Command Center and as a training site for crew qualification.

Day-to-day crew operations for NORAD and USNORTHCOM typically take place at Peterson Air Force Base.

[6] In early 2015, Admiral William E. Gortney, commander of NORAD and NORTHCOM, announced a $700 million contract with Raytheon to move systems into the complex to shield it from electromagnetic pulse attack, with additional work to be done at Vandenberg and Offutt.

[69] On June 24, 1994, when the "Joint Task Force – Cheyenne Mountain Operations organization was brought online to take responsibility for the installation", Brig.