The world is facing a ‘new era’ of terrorism after the US strikes on Iran, experts warned yesterday.

Donald Trump’s surprise decision to attack Tehran’s nuclear facilities – just days after the US President seemed to back away from the idea – radically increases the risk of ‘likely’ retaliation, former UK national security adviser Lord Ricketts cautioned.

While the UK was not involved in the action, the Government was informed before the strikes happened, ministers confirmed yesterday.

Despite speculation any attack could be launched from the joint UK/US airbase on Diego Garcia – where the B-2 stealth bombers used have previously been based – the mission was flown from mainland America, leaving Britain to watch on with the rest of the world after the raids took place.

Lord Ricketts said the Government would be ‘relieved’ to have been left out of the operation.