An aircraft designed to withstand nuclear blasts has been spotted flying across the English Channel.
Nicknamed the 'Flying Pentagon', the plane is a Boeing 747 E-4B originating from the Cold War period, designed to provide an airborne base for the US President, defence secretary, and senior military personnel to conduct operations in the event of nuclear warfare.
Based in Washington, US, at least one Nightwatch aircraft has been kept on hand 24/7 since the 1970s.
As tensions continue to mount globally as a result of Russia's ongoing invasion of Ukraine, it is no surprise that NATO has increased military resources on the Eastern Front of the continent.
Fears of nuclear war have also escalated, as President Vladimir Putin announced that he has placed his nuclear resources on full alert.
He previously refused to rule out the use of nuclear weapons if he believes Russia's position is threatened.
The E4-B - GRIM99 - was spotted taking off from Washington, after which it passed over the Atlantic and English Channel.
According to Flight Radar, the aircraft is currently circling an area just north of Cambridge, and it is thought the plane is headed for RAF Mildenhall, as per The Express.
Designed during the Cold War, the Nightwatch can fly for 12 hours without landing, while aerial refuelling means it can actually stay in the air for days.
Its main priority is withstanding the electromagnetic pulse from nuclear blasts.
The aircraft has three decks which aims to house a crew of 112, consisting of a number of military analysts, strategists and communication aides who would help Joe Biden through the event of nuclear war.
Inside, it boasts 18 bunks and six bathrooms, a briefing room, conference room, work areas and executive quarters.
However, the interior and furnishing is said to be functional, designed with its military role in mind, unlike Air Force One.
The aircraft has a bubble on top called a 'ray dome', which contains dozens of satellite dishes and antennae which can communicate with any US ship, submarine or aircraft around the world at any given time.
Although the planes are not a secret, they are rarely mentioned in the public domain and their full capabilities are classified
Russia also has a 'doomsday plane' - a Ilyushin Il-80 model known as Maxdome.
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Featured Image Credit: Alamy/TwitterTopics: World News, UK News, Ukraine, Russia