The United States has withdrawn its B-1 bombers from a British air base, a week after several men were arrested on suspicion of preparing terrorist acts at the facility. A Pentagon official confirmed the move on Sunday, citing operational security concerns.

Around a dozen B-1 bombers were stationed at RAF Fairford, an air base located northwest of London. The aircraft were used by the US in strikes against Iran. The Pentagon said all bombers deployed to the base have now returned to their home stations in the United States.

"While operational security precluded ⁠us from confirming the movement of our assets and forces in real-time, we can acknowledge now that all US bombers that were deployed to RAF Fairford have redeployed to their home stations in the United States," a Pentagon spokesman wrote in an email.

The withdrawal came after British authorities arrested several men at the base over suspected plans to carry out terrorist acts. The incident raised security concerns around the facility, which has played a key role in US military operations in the region.

British Prime Minister Andy Burnham said on Wednesday that the UK had "strong indications" that Iran was involved in the suspected plot targeting the base. Iran has rejected the allegations and called the accusations against Tehran baseless. The Iranian government also summoned the British ambassador in Tehran over the claims.

The Wall Street Journal first reported that the US had removed the aircraft from RAF Fairford. The report linked the move to growing security concerns over suspected terrorist plots targeting the military facility.

The UK government had allowed the United States to operate bombers from Fairford for strikes against Iranian missile sites. Those sites had been used to attack ships in the Strait of Hormuz, a key international shipping route.

US President Donald Trump said those behind the suspected plot had planned "big damage". US Secretary of State Marco Rubio also said the incident involved the "hands of a foreign actor."

The arrests and the suspected plot have added to security concerns surrounding RAF Fairford, which hosts US military aircraft during overseas operations. The B-1 bombers have now left the British base and returned to the United States.