The first new bomber in 30 years could cost nearly $700m each and can carry nuclear and conventional weapons.

As expected, specific details of the aircraft remain shrouded in secrecy.

But US Defence Secretary Lloyd Austin said it was “a testament to America’s enduring advantages in ingenuity and innovation.”

The B-21 Raider was unveiled during a ceremony on Friday at manufacturer Northrop Grumman’s facility in California.

Mr Austin said the plane would offer significant advances over existing bombers in the US fleet, stating that “even the most sophisticated air defense systems will struggle to detect the B-21 in the sky”.

“Fifty years of advances in low-observable technology have gone into this aircraft,” he said.