Shocking amount it costs 'Doomsday plane' to fly as one was seen circling nuclear command base causing officials to release statement

The shocking amount it costs to fly a US 'Doomsday Plane' has been revealed after one was spotted circling a nuclear command base this week.

The Navy's Boeing E-6B Mercury aircraft, ominously titled a 'Doomsday Plane,' was seen flying around parts of the Midwest on Monday (March 10) which prompted security officials to release a statement.

Such jets reportedly provide 'survivable, reliable and endurable airborne Nuclear Command, Control, and Communications (NC3) for the president, secretary of defense and U.S. Strategic Command,' according to Navair, and are worth upwards of $140,000,000 each.

The Air Force's E-4B jet being refueled mid-flight (USAF)

Clearly not your average jet, the planes have the capacity to remotely launch Minutemen intercontinental ballistic missiles, and can refuel while airborne to permit 72 hours of straight flying.

The E-6B is an upgraded, or rather 'blinged out,' version of the E-4B, and is the only jet of the 'Doomsday' kind that actually has the capacity to launch nuclear missiles, according to Intergalactic.

It also has the power to communicate with submarines, thanks to its five-mile-long antenna.

While day-to-day costs of that specific plane are yet to be revealed, its sister and much larger Air Force jet, the E-4B Nightwatch, has a similar role to play in the event of a nuclear catastrophe - and comes with eye-watering operation costs.

The Nightwatch, known as the 'flying Oval Office' or the 'flying war room', is essentially a military command center in the sky that is able to survive a ballistic attack and protect the POTUS and other senior officials.

The Navy's E-6B Mercury was spotted in the skies this week (NAVAIR)

As well as springing into action in the event of a national emergency, the Secretary of Defense gets to use it for international travel and press briefings.

While many details about the Nightwatch remain classified, the US Air Force has revealed there are just four in its fleet - and costs more than a pretty penny.

Each E-4B jet costs $223.2 million to build, reports Business Insider, and a further $159,529 per hour to operate.

The Nightwatch planes are on 'continuous alert', 24 hours a day, 356 days a year, with one believed to have been on permanent stand-by since 1975 amid the Cold War.

They can also traverse the skies for days at a time without needing to land, and come equipped with specialized masks to keep pilots from being blinded from nuclear blasts.

Its windows can also withstand electromagnetic shockwaves.

US Presidents Jimmy Carter and Ronald Reagan are the only two presidents to have ever publicly boarded the E-4B, as per AirForceTimes.

The US Air Force's E-4B jet often carries the Secretary of Defense (Jacquelyn Martin-Pool/Getty Images)

With this in mind - and considering the E-6B has that added nuclear capability - the jet spotted this week probably shares similar operating costs, if not more.

Over the years, all 16 of the Navy's E-6Bs have had modifications, several of which are currently being upgraded with a deadline of 2027 as part of a $111 million contract.

According to Naval News, Captain Adam Scott said the improvements ensure the jets can perform their 'nuclear deterrence mission better than ever' and will permit the fleet to 'successfully execute their mission for years to come.'

The E-6B Doomsday jet departed from its Tinker Air Force Base in Oklahoma at around 9am on Monday (March 10) before circling around Nebraska and the city of Omaha before heading back home some seven hours later.

US Strategic Command spokeswoman Karen Singer said the deployed jet was 'pre-planned' and 'purely coincidental' to President Donald Trump's tariffs announcement, which kicked the trade war up a gear amid growing tensions between the US, Canada, Mexico and China.