That economy-class seat you once occupied while flying in Asia might one day be the very place from where the United States nuclear weapons arsenal is controlled, Paralel.Az reports citing BBC.

That’s because five Boeing 747 passenger jets once operated by the South Korean flag carrier Korean Air have been purchased by the Sierra Nevada Corporation, the contractor for the replacements for the US Air Force’s current fleet of strategic command and control military aircraft, more commonly known as “Doomsday” planes.

Also known as the E-4B “Nightwatch,” the Doomsday planes are designed to be command-and-control centers for the US military in the event of a national emergency that sees command facilities on the ground destroyed or incapacitated, such as nuclear war.

They could become what amounts to a Pentagon in the sky, taking aboard the US president, secretary of defense and members of the Joint Chiefs among more than 100 other people with the ability to control US forces worldwide from the aircraft, according to an Air Force fact sheet on the E-4Bs.

The Doomsday planes are built to withstand the effects of an electromagnetic pulse, the burst of energy released by a nuclear explosion that can “disrupt and permanently damage electrical components and entire systems within most critical infrastructure sectors and impact large-scale infrastructure,” according to the US Department of Homeland Security.

At least one Doomsday plane is on alert 24/7 at a US military base somewhere in the world, the Air Force says.

On Friday, a spokesperson for the Colorado-based Sierra Nevada confirmed the purchase of the Korean Air jets but would not give any further details.

However, on April 26 the Air Force awarded Sierra Nevada a $13 billion contract to develop and produce the Survivable Airborne Operations Center, the official name of the new Doomsday plane. Work on the project is to be completed by 2036, according to a Defense Department release.

On Friday, an Air Force spokeswoman confirmed the contract had been awarded in April.

“The development of this critical national security weapon system ensures the Department’s Nuclear Command, Control, and Communications capability is operationally relevant and secure for decades to come. To satisfy operational requirements, the weapon system will be comprised of a Commercial Derivative Aircraft that will be hardened and modified to meet military requirements,” Air Force spokeswoman Ann Stefanek told CNN.

Last year, Sierra Nevada opened a 100,000-square-foot aircraft repair, maintenance and overhaul facility at Dayton International Airport in Ohio, and construction on a second hangar of similar size has begun.

An artist’s rendering of the Dayton facility showed a 747-800 inside.

The 747-800s would be an upgrade on the older and smaller 747-200 airframes of the current Doomsday fleet, which entered Air Force service in the 1980s.

Earlier this week, Korean Air announced the $675 million sale of five of its aircraft to Sierra Nevada. The decision to sell the jets was part of a “mid- to long-term introduction plan for new aircraft,” the airline said in a statement, adding it expects the deal to be completed by September 30, 2025.

Korean Air had nine 747-800 passenger jets in its fleet as of October 2023, according to its website.