https://en.m.wikipedia.org/wiki/National_Military_Command_Center

Looking Glass (or Operation Looking Glass) is the code name for an airborne command and control center operated by the United States. In more recent years it has been more officially referred to as the ABNCP (Airborne Command Post).[1] It provides command and control of U.S. nuclear forces in the event that ground-based command centers have been destroyed or otherwise rendered inoperable. In such an event, the general officer aboard the Looking Glass serves as the Airborne Emergency Action Officer (AEAO)[2] and by law assumes the authority of the National Command Authority and could command execution of nuclear attacks. The AEAO is supported by a battle staff of approximately 20 people, with another dozen responsible for the operation of the aircraft systems. The name Looking Glass, which is another name for a mirror, was chosen for the Airborne Command Post because the mission operates in parallel with the underground command post at Offutt Air Force Base.[3]