British counter-terrorism police arrested five men near RAF Fairford in Gloucestershire on Sunday, after residents reported three suspicious vans heading toward the US airbase. The men were first held on suspicion of Explosives Act offences, then further arrested on suspicion of preparation of a terrorist act, police said.

The arrests followed residents’ tip-offs at about 12:45 am, police said. About 85 homes were evacuated, a 400-metre cordon was set up, and Army bomb disposal units were deployed near Whelford. Counter Terrorism Policing’s Vicki Evans said “five men remain in custody” and called it the “early stages of an investigation”.

President Donald Trump praised the arrests in Chicago, claiming the men were “looking to do big damage” and had been “under investigation for a long time” by US and British authorities. But the BBC and the Guardian reported, citing sources, that the operation was not intelligence-led and that residents’ tip-offs were key. The suspects are unidentified and the motive is undisclosed.

RAF Fairford is the USAF base used by US long-range bombers for strikes against Iran, according to multiple outlets. The US Embassy in London urged Americans to exercise caution. Police say the investigation is ongoing and more updates will follow.