UK Prime Minister Keir Starmer on Monday said that British military bases in Greek Cyprus "are not being used by U.S. bombers" during the U.S.-Israeli war with Iran.

Britain's Akrotiri air force base on Greek Cyprus came under attack by an unmanned Iranian drone that hit the base's runway.

As he spoke to parliament, Starmer said the strike "was not in response to any decision that we have taken," adding that the British government believed the drone "was launched prior to our announcement".

Iran's approach is becoming "more reckless and more dangerous", Starmer said.

"They are working ruthlessly and deliberately through a plan to strike, not only military targets, but also economic targets in the region, with no regard for civilian casualties. That is the situation we face today and to which we must respond."

He also defended his decision to keep Britain out of the U.S. and Israel's initial strikes against Iran following criticism from President Donald Trump.

Trump told Britain's Daily Telegraph he was "very disappointed" with Starmer's initial refusal to let Washington use British military bases in the US-Israeli war against Iran, launched on Saturday.

"President Trump has expressed his disagreement with our decision not to get involved in the initial strikes, but it is my duty to judge what is in Britain's national interest," Starmer said.

"That is what I have done and I stand by it," he added.

After initially refusing to have any role in the strikes, Starmer on Sunday announced that he had agreed to a U.S. request to use British military bases for a "specific and limited defensive purpose".

His Downing Street office said the prime minister took the decision after Iran fired missiles over the weekend that put British interests and people "at risk".

"We all remember the mistakes of Iraq, and we have learnt those lessons. Any UK actions must always have a lawful basis and a viable thought-through plan," he told lawmakers.