The US paraded almost its entire fleet of nuclear stealth bombers in a massive show of force as the Middle East teeters on a knife edge.

The B-2 Spirits – saved only for the “most important missions” – are “ready to execute a global strike anytime, anywhere,” the US Air Force warned.

The B-2 Spirit is a multi-role, heavy bomber capable of delivering both conventional and nuclear warheads.

The 1000kmh beasts are designed to be virtually invisible to radar and are the world’s most expensive aircraft, estimated to cost £1.6billion each.

The two-pilot jet has an unrefueled range of 6,000miles and is specifically built for intercontinental missions.

As tensions spiralled earlier this week as Israel promised it would carry out a “significant response” to Iran’s aerial attack last weekend, the US was testing its stealth bombers.

Twelve of the entire fleet of 20 B-2 Spirit’s performed a fearsome so-called “elephant walk” and flight routine.

The rarely-seen aircraft were amassed as part of the “Spirit Vigilance” training exercise which focuses on increasing the readiness of the airmen to carry out a stealth bomber mission.

The impressive aeronautic challenge involves the jets taxiing together in close formation and a minimal interval takeoff.

The aircraft, assigned to the 509th Bomb Wing, were seen on the runway at Whiteman Air Force Base, Missouri on Monday.

The US Air Force said: “The routine training ensures that Airmen are always ready to execute global strike operations… anytime, anywhere.”

Speaking about “Spirit Vigilance”, Col. Geoffrey Steeves, commander of the 509th Operations Group, said: “This is a reminder that the B-2 Spirit bomber is the visible leg of nuclear triad.

“Simply put, the B-2 is the world’s most strategic aircraft.

“It is the only aircraft on the planet that combines stealth, payload, and long-range strike.

“We are charged with delivering the nation’s most powerful weapons for our most important missions.”

The spectacular show of American airpower comes as Israel launched its much-awaited revenge attack on Iran this morning after repeated calls from the US for restraint.

The precision strike hit a major Iranian air force base next door to one of its prized nuclear sites near the city of Isfahan – just days after Tehran unleashed an unprecedented missile and drone blitz.

Iranian state TV launched into damage control claiming three drones were “destroyed” by its air defence batteries and no ground damage was caused.

However, the fresh attack threatens to further push relations between the two arch-foes to the brink amid fears of an all-out war breaking out across the tinderbox of the Middle East.