LONDON (AP) — U.K. police said that five men arrested in the early hours of Sunday near an air base used by the United States during its war against Iran are being held on suspicion of preparing a terrorist act that appeared to involve three trucks.

London’s Metropolitan Police, which takes the lead on potential terrorist activities, said police received a call at 12:45 a.m. related to the three suspicious vehicles that appeared to be traveling toward RAF Fairford, a U.K.-owned base that is operated by the U.S. under an agreement dating back to the Cold War.