Not long after the CIA declassified past presidents' acts to ensure the government survived a nuclear explosion, Garrett Graff has an inside look at what President Donald Trump will fly after a blast.

In a Tuesday Politico story, Graff expands on his latest book, Raven Rock: The Story of the U.S. Government's Secret Plan to Save Itself--While the Rest of Us Die detailing the communications and security infrastructure around the president of the United States. Critics have attacked Trump's frequent trips to Mar-a-Lago for the exorbitant $3 million price tag. That doesn't include secret costs affiliated with presidential travel.

Graff cites a GAO study that claims it could be as much as $100 million annually for the $180,000 per hour cost of flying "Air Force One." The costs don't merely come from the hundreds of military staff required to handle the security detail, there's a whole other force behind the plane that no one sees. According to Graff, the U.S. "has been building and equipping a special set of planes whose sole purpose has been to evacuate the president in the event of a nuclear war and allow him to command a war from wherever he may be."

It's not "technically" a secret, but the Air Force doesn't publicly admit it exists. He did a careful review of the Air Force manuals and other historic documents that outline where the planes land after picking up the president. One key thing Air Force One does that no other 747 can is what was witnessed Sept. 11, 2001, when the plane took off with George W. Bush in Florida. In an emergency, the plane can take off so fast and climb to a high altitude it left many on the flight at the time a little shaken.

Another set of four 747s exists that can be used as the "National Airborne Operations Center" known as E-4B Nightwatch planes. While Air Force One is a comfortable in-flight Oval Office, the Nightwatch is a flying war-room with dozens of military analysts prepared to assist the president through the beginning of a nuclear war. They're outfitted with a five-mile-long wire antenna that guarantees the president can reach the fleet of nuclear submarines if the U.S. has been destroyed.

The so-called “Doomsday” planes are known to crews as “Air Force One When It Counts.” At least one of those Nightwatch planes is with the president on most trips, particularly international trips. One even awaits in Omaha, Nebraska with its engines running 24-hours a day.

That doesn't even count the prep-work required before a presidential trip. Additional trips, codenamed PHOENIX BANNER flights, deliver the armored vehicles, helicopters and other secure transportation. Another white unmarked jet accompanies the president, but at another airport, to evacuate the president in an emergency and "preserving the so-called National Command Authorities, the officials with authority to launch nuclear weapons," Graff explained.

The C-20Cs don't officially exist, but wherever the president goes, they have their own parallel trips and blend in with other aircraft at a different airport. On Sept. 11, 2001, the C20C stood by at Patrick Air Force Base while Bush's Air Force One was parked at Homestead Air Force Base in Miami. They were brought into the nuclear fallout mix during President Ronald Reagan's investment in “continuity of government” operations.

A 2013 video shows what one of the Nightwatch planes looks like on the inside. Watch below: