One of the five men arrested near RAF Fairford in the early hours of Sunday morning had dialled 999 himself, the BBC understands. The suspect reportedly called police at 00:45 BST, almost an hour before a local farmer also raised the alarm after spotting men in balaclavas.

The five men were initially arrested on suspicion of explosives offences and later terrorism offences. The arrests followed the spotting of three vans near the Gloucestershire airbase, which is operated by the US military, prompting a significant security response. Searches of the vans revealed a quantity of petrol but no explosive devices.

Police were alerted to the suspicious vehicles in Whelford by the farmer, who described finding the road blocked by a large group of hooded and masked men. She stated that her 999 call likely foiled any plans the individuals may have had. The subsequent police operation included the arrival of a bomb disposal team and the establishment of a 400-meter cordon.

Assistant Commissioner Laurence Taylor, head of Counter Terrorism Policing, indicated that the police response was based on a "range of information." He noted that the five men, all UK nationals aged between 23 and 25, were released on bail on Monday as an "investigative decision grounded in experience and strategy." Police cordons are expected to be lifted entirely on Wednesday, and residents from evacuated homes have been permitted to return.

The five men, four of whom reside in Westminster and one in Camden, remain under investigation with stringent bail conditions restricting their movement and contact. Taylor emphasized that public safety was paramount in their decision-making process, acknowledging that the bail decision might have appeared surprising to some.

The RAF Fairford base has a long history of use by the US Air Force, including recently as a location for US bombers undertaking missions to the Middle East following UK approval for defensive strikes on Iran. This international context was highlighted by US President Donald Trump, who expressed disappointment over the men's release on bail.

Authorities are exploring various lines of inquiry, including the potential involvement of proxies or individuals acting for a foreign state, knowingly or unknowingly. Taylor acknowledged the concern the incident generated, exacerbated by international commentary.

Prime Minister Andy Burnham chaired a COBRA meeting to discuss the situation and urged the public to avoid speculation while investigations continue to establish the full facts.