FAIRFORD, England (AP) — Police were holding five men on Monday and examining suspected explosives found near a U.S.-operated air force base in England, as counterterror detectives investigated whether the arrests foiled an attempted attack linked to Iran.

The men were detained early Sunday after three vans were spotted near RAF Fairford, a U.K.-owned base that has been used by American bombers during decades of conflicts in the Middle East.

Investigators have...