British counterterror police have released on bail five young men arrested over a suspected bomb plot targeting a US-operated air force base in England, raising questions on both sides of the Atlantic.

The five British nationals, aged 23 to 25 and all from London, were arrested early on Sunday, September 27, near RAF Fairford on suspicion of explosives and terrorism offences. Three vans linked to the suspects were stopped near Whelford. Police confirmed on Tuesday that no explosives were found in the vans.

The men were freed on Monday after about 38 hours in custody. Laurence Taylor, head of UK Counter Terrorism Policing, said the suspects face stringent conditions and absolutely remain under investigation. He called the decision an investigative one grounded in experience and strategy.

US President Donald Trump said he was surprised by the release. “I wouldn’t have done that,” he told reporters. Secretary of State Marco Rubio said the case clearly involves the hands of a foreign actor but named no country.

Police are examining multiple lines of inquiry, including a possible link to Iran. Tehran has denied any involvement. About 85 evacuated households were allowed to return on Monday.