Five men arrested on Sunday on suspicion of terrorism and explosives offences near RAF Fairford in Britain have been released on bail after what authorities described as extensive interviews. They face strict limits on travel and contact with others. None has been charged, and investigators say the case remains open along several lines of inquiry.

Counter Terrorism Policing said all five are British nationals from London, aged 23 to 25. They were detained near the base with three vans. Laurence Taylor, head of UK Counter Terrorism Policing, said investigators are considering every possibility, including whether proxies or individuals knowingly or unknowingly acted for a foreign state. He did not say that any such link had been established.

RAF Fairford is a major European hub for the U.S. Air Force and a staging point for long-range operations in the Middle East. The base has been used by American B-52 and B-1 bombers during the ongoing war with Iran. British authorities have not confirmed a connection between Iran and the suspected plot.

Defence Secretary Wes Streeting thanked a farmer who contacted authorities after seeing hooded and masked men and three vans in Whelford, near the base, early Sunday. The farmer told the BBC she believed officials had allowed the suspected attackers to get too close. Streeting said the caller had only a partial picture and declined to discuss operational security.

Iran’s embassy in London denied involvement and condemned what it called unfounded speculation in British media. Streeting also said he was not drawing a connection with Iran, while referring generally to threats from Iran and its proxies. The five men remain under investigation and have not been charged.