U.K. prime minister attributes plot against U.S. bomber base to Iran

British Prime Minister Andy Burnham told the UK House of Commons Monday that Iran's Revolutionary Guard was "almost certainly" behind the suspected plot to attack the RAF Fairford base where U.S. bombers were stationed.

Why it matters: This was the first time the UK officially blamed Iran for the alleged planned attack.

What he said: "I can confirm our assessment that it is highly likely to have been coordinated in Iran, almost certainly directed by the IRGC.

We will not tolerate these threats on our soil," Burnham said.

Driving the news: Ten days ago, the U.S. evacuated a dozen B-1 strategic bombers from RAF Fairford in response to intelligence indicating an Iranian drone attack.

It would have been an unprecedented and brazen move by Iran against a U.S. base in Europe — with the potential to dramatically escalate the war in the Middle East.

The decision to move the bombers came several days after British security forces arrested several dual British-Iranian citizens suspected of planning an attack on the base.

It was unclear whether the people who were arrested were connected to the alleged planned drone attack or if they were planning a different attack.

Israeli Prime Minister Benjamin Netanyahu said Israel provided the UK with intelligence that pointed to a threat of an Iranian attack.

State of play: British Foreign Secretary Ed Miliband said Monday that the Iranian ambassador was summoned to the foreign office in London to denounce the alleged Iranian plot.

What they're saying: The U.S., UK and 27 other western countries published a joint statement on Monday condemning Iran for "use of violent attacks, including the acts of lethal plotting, arson, sabotage, cyber-attacks, and other hybrid activities against us and our partners." The group said the threat against RAF Fairford "demonstrates the IRGC's continued willingness to project hostile activity beyond its borders through covert networks and proxy actors."