Yes, the United States operates a fleet of four Boeing E-4B "Nightwatch" aircraft, commonly referred to as the "Doomsday Planes." Officially designated as the National Airborne Operations Center (NAOC), these highly modified 747-200s serve as a mobile command hub for the President, the Secretary of Defense, and the Joint Chiefs of Staff during national emergencies, such as a nuclear conflict. The E-4B is designed to withstand an Electromagnetic Pulse (EMP), features thermal and nuclear shielding, and carries advanced satellite communication equipment that can reach any military asset globally. At least one E-4B is kept on 24/7 high-alert status at all times. In 2024, the U.S. Air Force awarded a contract to Sierra Nevada Corp to begin developing the "Survivable Airborne Operations Center" (SAOC), which will eventually replace the aging E-4B fleet by the 2030s.