LONDON (AP) — A surprise decision by the U.K.’s counterterrorism police to release five suspects on bail during an investigation into a suspected bomb plot at a U.S.-operated air force base in England has deepened questions and uncertainty about the incident.

Police confirmed Tuesday that no explosives were found in three vans linked to the suspects, and said the decision to grant bail was grounded in “experience and strategy.”

U.S. President Donald Trump told reporters on Monday that he was surprised he five young British men who were arrested Sunday on suspicion of explosives and terrorism offenses near the RAF Fairford base were freed a day later.

“I wouldn’t have done that,” Trump said.

The base has been used by American bombers during decades of conflicts in the Middle East, including this year’s war with Iran. Counterterror detectives have said they were investigating “multiple lines of inquiry,” including whether the suspects had a link to Iran. Iran has denied involvement.

The head of U.K. Counter Terrorism Policing, Laurence Taylor, stressed that the suspects — all British nationals in their 20s — face stringent conditions and “absolutely remain under investigation.”

“Now I understand why this development was surprising to some, but I would like to reiterate that this is an investigative decision, and one which is grounded in experience and strategy,” he said.

Taylor said people’s concerns about the incident were being “heightened by the international commentary that we are seeing.”

In an interview with Fox News, U.S. Secretary of State Marco Rubio said the case “clearly involves the hands of a foreign actor,” but did not name a specific country or give more details.

“I know a lot of people are disturbed by the news that some of these people have been released on bail, as some of the people are being investigated,” he added.

Police found no explosives in suspicious vehicles

A police cordon remained in place around three vans found close to the Fairford base on Tuesday, as armed police and counterterrorism officers continued to examine the scene.

A local farmer said she called police after seeing the vans blocking a road near the air base as she drove home in the early hours of Sunday. She said she came across a group of men, some with their faces covered, nearby, and that the men ran away when they saw her vehicle.

Earlier, army bomb-disposal experts used a robot to examine the vans. Taylor said “a quantity of petrol was recovered” from the vans, but no explosives.

Officials hint at possible Iran role

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

Investigators haven’t concluded whether the incident was state-backed or what the motive was, but authorities have strongly hinted that Iran is possibly involved. They are also investigating a possible link to Russia or non-state militant groups. RAF Fairford has also been the focus of protests by anti-war campaigners.

Defense Secretary Wes Streeting said the U.K. “shouldn’t be cowed by saber rattling from Iran,” adding that “the Iranian regime is one that wishes harm to our country, our allies, and the freedom and democracy that we enjoy.”

The Iranian embassy denied the country’s involvement in the suspected plot.

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.

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.

British officials have said the number of national security cases involving activity by hostile states, including Iran, increased by 50% in the six months to December 2025.

Questions about possible security or intelligence failures

It was unclear whether the arrested men had been on the security services’ radars. Local residents described seeing heightened security around RAF Fairford in recent days, with heavy vehicles parked across entrance gates.

Trump said the suspects were detained following cooperation between the U.S. and Britain, and had been “under view” for some time. Police, however, said the arrests were triggered by a late-night call about the suspicious vehicles near the base.

The farmer who called the police, who didn’t want to be named, alleged that her call to police may have foiled the suspected plot. She added that several hours passed between her call and when police “suddenly decided to evacuate people” in the area.

“But meanwhile, those vans were right in the middle of the village next to everyone’s houses and no one did anything,” she said.

Streeting, the defense secretary, said Monday that the farmer only had a “partial picture” of the operation.

Local lawmaker Roz Savage said there was “anger and anxiety” from residents, especially those who were evacuated from their homes and still haven’t been able to return.

“I have so many questions right now, more questions than answers,” she said in a video message on X. “This should not have been allowed to happen.”