A 'doomsday' US warplane built to withstand a nuclear attack met its match when a bird strike forced it to land.

The US Navy E-6B Mercury aircraft – designed to be an airborne command centre in the event of nuclear conflict – was flying on an exercise when one of its four jet engines was struck by the unidentified bird, reports Navy Times.

The incident earlier this month was declared a "Class A mishap" by officials, meaning it could cause more than USD$2 million (AUD$2.9 million) of damage as well as death or permanent injury.

The plane was taking part in a 'touch-and-go' landing'– where the pilot lands and takes off again without halting – at a Maryland airfield when the bird strike happened.

A file photo of a US Navy E-6B Mercury aircraft. (US Air Force) (Supplied)

A spokesman for the US Navy said the aircraft landed safely after the collision. There were no reported injuries.

The damaged engine has been replaced and the plane is now back in service.

Equipped with technology to survive electromagnetic pulses from exploding nuclear bombs, the E-6B Mercury is a military variant of the Boeing 707.

The plane carries low-frequency communications systems to enable the US president and military commanders to direct nuclear forces on land, sea and air, reports Military.com.

It is also equipped with an airborne launch control system, enabling it to fire land based intercontinental ballistic missiles.

The E-6B Mercury is fitted with advanced technology designed to withstand nuclear attack. (US Air Force) (Supplied)

There are about 3000 wildlife-strike incidents involving military aircraft every year, according to US Department of Defence.