NEW YORK/LONDON: The United States has withdrawn its B-1 bombers from a British air base, days after five men were arrested near the facility on suspicion of preparing terrorist acts in a case that British authorities have described as complex.

The bombers had been based at RAF Fairford, about 90 miles (145 km) west of London, and had recently been used in U.S. strikes against Iran. A Pentagon official said on Sunday that the aircraft had returned to their home bases in the United States.

The move came about a week after five British men in their 20s were arrested near the base. They were reportedly seen running into fields from three white vans parked close to the facility. Police said no explosives were found, although a quantity of petrol was discovered.

The five men have since been released on bail. A sixth man, a dual UK-Iranian national who was arrested separately on suspicion of preparing terrorist acts, has also been released on bail.

The arrests remain largely unexplained. British counterterrorism police have described the investigation as complex.

British Prime Minister Andy Burnham has said the suspected plot was likely backed by Iran. Iran has rejected the allegations, saying claims of involvement were baseless.

Iranian Foreign Minister Abbas Araqchi criticized the decision to release the suspects on bail. He wrote on X: "I can confirm Iran's belief that releasing supposed terrorists working for foreign states really says it all. You're barking up the wrong tree."

RAF Fairford is one of the few U.S. Air Force bases in Europe capable of operating heavy bombers. It has played an important role in previous U.S. military operations in the Middle East.

During the current conflict, the United States had permission to use the base for strikes against Iranian missile sites that had been attacking ships in the Strait of Hormuz.

A Pentagon spokesman confirmed that the aircraft had left Britain and returned to the United States. The Pentagon also said the U.S. bomber fleet remained ready to carry out precision strikes anywhere in the world.

The Wall Street Journal, which first reported the withdrawal, said the bombers were moved because of security concerns linked to suspected plots against the base.

Britain's Ministry of Defense declined to comment on the U.S. aircraft's movements.

A senior NATO military official said the withdrawal would not affect the alliance's ability to respond to threats. The official said NATO's defensive capabilities remained strong because of the combined strength of its 32 member countries.

The arrests took place in the early hours of September 27. Police have not said what the men were allegedly planning or whether they had directly targeted the air base.

The U.S. decision to withdraw the bombers has added to questions about security at Fairford and the possible international links behind the suspected plot.

U.S. President Donald Trump said the suspects had planned to cause "big damage" and suggested the case could be connected to Iran. He also criticized the decision to release the suspects on bail, saying he would not have done so.