Exercise Global Thunder/Vigilant Shield

A firefighter from the Cheyenne Mountain Air Force Station Fire checks a passageway for smoke during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. The training was conducted in support of exercise Global Thunder/Vigilant Shield, an exercise designed to test the readiness of U.S. Strategic Command units. (U.S. Air Force photo by Steve Kotecki)

A firefighter from the Cheyenne Mountain Air Force Station Fire checks a passageway for smoke during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. The training was conducted in support of exercise Global Thunder/Vigilant Shield, an exercise designed to test the readiness of U.S. Strategic Command units. (U.S. Air Force photo by Steve Kotecki)

Capt. Emma Pinkerton, 21st Medical Group clinical nurse, performs CPR on a training dummy during a casualty training exercise at Cheyenne Mountain Air Force Station, Colorado, Nov. 3, 2017. The training incorporated a first response by the fire department with triage and treatment by the Medical Group. (U.S. Air Force photo by Steve Kotecki)

Capt. Emma Pinkerton, 21st Medical Group clinical nurse, performs CPR on a training dummy during a casualty training exercise at Cheyenne Mountain Air Force Station, Colorado, Nov. 3, 2017. The training incorporated a first response by the fire department with triage and treatment by the Medical Group. (U.S. Air Force photo by Steve Kotecki)

An entrance to Cheyenne Mountain Air Force Station, Colorado, converts to sleeping quarters during a training exercise on Nov. 2, 2017. During a training exercise or real world event in which the facility needs to be sealed up for an indefinite amount of time areas of the facility can be converted to living quarters. (U.S. Air Force photo by Steve Kotecki)

An entrance to Cheyenne Mountain Air Force Station, Colorado, converts to sleeping quarters during a training exercise on Nov. 2, 2017. During a training exercise or real world event in which the facility needs to be sealed up for an indefinite amount of time areas of the facility can be converted to living quarters. (U.S. Air Force photo by Steve Kotecki)

First Responders from the 721st Medical Squadron and Cheyenne Mountain Air Force Station Fire Department treat an acting patient who has suffered a fall during exercise Global Thunder/Vigilant Shield at Cheyenne Mountain AFS, Colorado, Nov. 2, 2017. The exercise is designed to test the readiness of Cheyenne Mountain AFS’s Airmen in the event of a crisis. (U.S. Air Force photo by Steve Kotecki)

First Responders from the 721st Medical Squadron and Cheyenne Mountain Air Force Station Fire Department treat an acting patient who has suffered a fall during exercise Global Thunder/Vigilant Shield at Cheyenne Mountain AFS, Colorado, Nov. 2, 2017. The exercise is designed to test the readiness of Cheyenne Mountain AFS’s Airmen in the event of a crisis. (U.S. Air Force photo by Steve Kotecki)

Firefighters from the Cheyenne Mountain Air Force Station Fire Department don their personal protective equipment during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. During a lock down event the firefighters live and work full-time inside Cheyenne Mountain AFS. (U.S. Air Force photo by Steve Kotecki)

Firefighters from the Cheyenne Mountain Air Force Station Fire Department don their personal protective equipment during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. During a lock down event the firefighters live and work full-time inside Cheyenne Mountain AFS. (U.S. Air Force photo by Steve Kotecki)

A firefighter from the Cheyenne Mountain Air Force Station Fire Department breaches a room in which the fire alarm has been activated during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. The fire department trains to work in tight enclosed spaces inside Cheyenne Mountain AFS as well as know the complex’s layout so they respond to an emergency quickly. (U.S. Air Force photo by Steve Kotecki)

A firefighter from the Cheyenne Mountain Air Force Station Fire Department breaches a room in which the fire alarm has been activated during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. The fire department trains to work in tight enclosed spaces inside Cheyenne Mountain AFS as well as know the complex’s layout so they respond to an emergency quickly. (U.S. Air Force photo by Steve Kotecki)

A firefighter from the Cheyenne Mountain Air Force Station Fire Department uses his radio inside a room in which the fire alarm has been activated during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. During training the fire fighters wear full personal protective equipment to simulate the conditions in which they would actually be responding to an emergency. (U.S. Air Force photo by Steve Kotecki)

A firefighter from the Cheyenne Mountain Air Force Station Fire Department uses his radio inside a room in which the fire alarm has been activated during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. During training the fire fighters wear full personal protective equipment to simulate the conditions in which they would actually be responding to an emergency. (U.S. Air Force photo by Steve Kotecki)

CHEYENNE MOUNTAIN AIR FORCE STATION, Colo. -- A firefighter from the Cheyenne Mountain Air Force Station Fire checks a passageway for smoke during a training exercise at Cheyenne Mountain AFS, Colorado, Nov. 3, 2017. The training was conducted in support of exercise Global Thunder/Vigilant Shield, an exercise designed to test the readiness of U.S. Strategic Command units. (U.S. Air Force photo by Steve Kotecki)