What to know about the suspected bomb plot against a UK air base used by the US in the Iran war

LONDON (AP) — British authorities are examining suspected explosives found near an air base in England used by the U.S. Air Force and whether five men arrested on terrorism suspicions — but later released on bail — are linked to Iran.

The suspects were detained shortly after midnight on Sunday after police stopped three vans traveling toward RAF Fairford, a U.K.-owned base that has been used by American bombers during decades of conflicts in the Middle East, including the ongoing Iran war .

Investigators have not concluded whether the incident is a state-backed attack. They are investigating a possible link to Iran, Russia or militant groups. Iran has denied involvement.

Details about the case are still emerging. Here's what we know — and don't know — about what happened:

Counterterror police said Monday that the five suspects are British nationals from London between 23 and 25 years old.

It's not clear why they were released on bail Monday. The head of U.K. Counter Terrorism Policing, Laurence Taylor, said that the suspects face stringent bail conditions and “absolutely remain under investigation.”

Taylor said lines of inquiry include that the suspected offenses were committed by “proxies or individuals, either knowingly or unknowingly, working on behalf of a foreign state.”

A local farmer told reporters she called emergency services after she found three vans blocking a road in the nearby village of Whelford. Later, dozens of households near the base were advised to evacuate while bomb disposal robots were used to examine the vans.

The air base houses the headquarters of the U.S. Air Force’s 501st Combat Support Wing and is a forward operating location for the U.S. Air Force Global Strike Command. Fairford was used during the 1990 Gulf War, the 2003 Iraq war and the U.S.-Israeli bombardment of Iran this year.

Defense Secretary Wes Streeting said the motive is not yet known. But he added: “We shouldn’t be cowed by saber rattling from Iran, and we shouldn’t be in any doubt that the Iranian regime is one that wishes harm to our country, our allies, and the freedom and democracy that we enjoy.”

Iran and allied militant groups have been accused of plotting or carrying out attacks on U.S. , British and Jewish targets in the past, allegedly acting through local proxies while denying responsibility.

Nigel Inkster, a senior adviser at the International Institute for Strategic Studies who formerly worked at the British Secret Intelligence Service, said Iran is known to have hired “low grade,” untrained proxies to commit crimes in the U.K. on its behalf. But it's not clear “what sort of threat these people posed,” he said.

“Was it a homegrown undertaking or one that was sponsored internationally, especially Iran? Were the devices sophisticated or crude? We have no idea,” he said.

“Driving three vans up to an air base with a perimeter doesn’t strike me as a particularly clever way to cause significant damage,” he added.

Iran's embassy to the U.K. condemned what it said were “unfounded and malicious speculations published by some British individuals and media outlets” linking it to the suspected plot.

It's unclear when security services became aware of the alleged plot and whether there were any lapses that allowed the suspects to get so close to the base.

U.S. President Donald Trump praised the response, telling reporters: “We had them under view for a long time, and we got them.”

“They were looking to do big damage to our fort, and working with the British worked out great,” he added.

Some residents have told British media that they noticed an increase in security near Fairford in recent weeks, suggesting authorities may have anticipated an incident there.

However, British police have said the arrests were triggered by a late-night call about suspicious vehicles near the base.

The farmer who called the police said she saw a group of about eight or 10 men, some with their faces covered, run away when they spotted her car. She said it took several hours between the call and when police “suddenly decided to evacuate people.”

“But meanwhile, those vans were right in the middle of the village next to everyone’s houses and no one did anything,” said the farmer, who declined to be identified because she was describing what she saw as potential security lapses.

Streeting, the defense secretary, said Monday that the farmer only had a “partial picture” of what’s been happening. He didn't elaborate, saying he was limited in what he could say regarding operational security.