One of the five men arrested near RAF Fairford called police himself before the farmer who was credited with raising the alarm, The Times reported. The farmer alerted police at 1:36 a.m. on Sunday after seeing three vans and men in balaclavas near the base, but the authorities were already on the scene because a suspect had called nearly an hour earlier, the newspaper understands. The suspect's motives for calling 999 are under investigation, and the police inquiry is focused on alleged Iran proxies.

The five men, all British nationals aged 23 to 25 and London residents, were arrested in Whelford, beside the base that hosts US B-1 and B-52 bombers used in strikes on Iran, and were held under the Explosives Act before being further arrested on suspicion of preparing a terrorist act. About 85 households were evacuated while army bomb disposal teams examined the three vans, one of which carried fake Fuel2You branding. Police found no improvised explosive devices in the vehicles, only a quantity of petrol, and released the men on bail under strict conditions. They remain under investigation while searches continue at London properties.

President Trump, who said the men had been under surveillance and were looking to do "big damage," renewed his criticism of the bail decision, asking "How do you give bail to a terrorist?" Secretary of State Marco Rubio has said the incident clearly involved a foreign actor, a claim Iran's embassy in London rejects. Analysts told Al Jazeera the quick release suggests police have little evidence, at this stage, that the men were plotting a major attack, though counter-terrorism officers are still pursuing multiple lines of inquiry, including possible foreign-state involvement.