The US withdrawal of all 12 B-1 bombers from RAF Fairford followed intelligence indicating that Iran's Islamic Revolutionary Guard Corps may have been preparing a drone attack targeting the aircraft and American personnel at the southern England base, according to US and British officials cited by The New York Times on Monday.

Officials said the suspected operation was part of a broader Iranian effort that could have involved multiple methods of attack against the several hundred US personnel stationed at Fairford. The American bombers were moved back to the United States over the weekend.

Vice President JD Vance said Monday that the Pentagon relocated the aircraft “out of an abundance of caution trying to protect our guys." He accused Iran of seeking to carry out terrorist attacks against Americans but declined to provide details about the specific threat.

“We do feel with some confidence that the Iranians are trying to do what the Iranian state has done for 49 years, which is engage in acts of terrorism against the United States and against a lot of other people as well," Vance told reporters at Joint Base Andrews before departing for Alaska. “We are being extremely cautious.

President Donald Trump also confirmed that threats against the bombers had prompted their return to the United States. “There were some threats," Mr. Trump told reporters. “Why should we leave them there?" he added.

The Wall Street Journal had previously reported that a drone threat was behind the withdrawal.

The developments come amid a British investigation that began after five men were arrested near RAF Fairford on September 27. The suspects had been traveling in white vans near the base, which has been used by US bombers during the US-Israeli war against Iran.

They were released on bail the following day after police found no explosives in the vehicles, although authorities have stressed that the investigation remains active. A British-Iranian dual national was arrested Thursday on suspicion of preparing terrorist acts.

British Prime Minister Andy Burnham said last week that his government believed Iran had been involved in planning the events that resulted in the arrests. Officials in the United States, Britain, Germany and Israel believe the suspected operation is linked either to Iran's Islamic Revolutionary Guard Corps or to another military command in Tehran. Iran has denied the allegations.

A spokesman for Burnham declined Monday to discuss military operations by other countries. Asked whether RAF Fairford was secure, he said it was and referred to comments by British Defense Secretary Wes Streeting, who last week said Britain had “tried and tested approaches to defend our bases around the country and throughout the world."