Donald Trump’s decision to move US B-1B bombers from a UK airbase citing terror threats may embolden Iran and Russia’s use of proxies to carry out sabotage attacks, according to current and former British officials.

While stressing any decision about American military hardware is for Washington, the UK is concerned that hostile states will take confidence that they can force changes to Western defense arrangements and destabilize their enemies for the relatively small cost of hiring local criminal proxies, the people said, speaking on condition of anonymity about sensitive matters.

Those concerns hint at nascent tensions between Burnham’s weeks-old UK government and Trump’s administration after the president said the aircraft “didn’t fly out by accident” from RAF Fairford in western England, and suggested they had been moved away rather than “tempt the enemy.”

The UK government declined to comment. A senior administration official said the US always acts out of an abundance of caution, and that its forces are well equipped to meet any potential threat posed by Iran. A War Department official said the US would continue to asses threats around bases it uses and “take appropriate actions to protect our people.”The planes were flown out in the wake of a plot against the base in which Prime Minister Andy Burnham has said it is likely Iran was involved. It’s resulted in the arrest of a number of men on suspicion of preparing terrorist acts, though many of have since been released on bail under tight restrictions, with investigators stressing they are keeping an open mind about what happened.

Threats from Iran against RAF Fairford, which the US has used as a launchpad for some of its operations in the Middle East, have risen as a result of the war. Echoing Trump’s remarks that the planes had been removed to lower the risks, Vice President JD Vance told reporters this week that they’d been shifted “out of an abundance of caution, trying to protect our guys.”Nevertheless, British defense officials are confident the base is highly secure and that the full range of threats is being closely monitored. They consider the threats serious but the risk of a successful attack low.

Guard patrols had been increased before the incident, with more surveillance including counter-drone equipment put in place, people familiar with the matter said. While drones may be one of a number of different threats to the base along with other forms of sabotage, that doesn’t mean there is a high chance of an attack successfully breaching the base’s multiple layers of security, they said.

Military officials from other nations which host UK bases have contacted British counterparts since the US decision to move its bombers to ask if the risk to their own countries had increased, and had to be reassured that the bases were well-defended, people familiar with the conversations said.

While some US officials have speculated that Iran could have been seeking to emulate Ukraine’s spectacular drone attack that successfully destroyed a number of Russian bombers last year, known as Operation Spiderweb, current and former UK officials disputed the likelihood of such an attack being pulled off.

“People grossly underestimate how many moving parts and how much complex logistics are involved in doing any kind of small drone ops, much less something like Spiderweb,” said Faine Greenwood of drone consultancy Tarentum Consulting.

Communication between the US and the UK about why the bombers were withdrawn was limited and left some senior UK officials confused about the rapid redeployment, other people familiar with the situation at the base said. The US has a low risk tolerance for threats against its kit, they added.

“Whatever the motivation or reason for the US withdrawal, its messaging and handling has been at best ambiguous, and at worst very damaging to both the relationship and the perceptions of relative security of UK bases,” said Greg Bagwell, a former RAF senior commander who is now president of the UK Air and Space Power Association. “It belies the actual truth about how joined up the UK and US are in managing and actioning shared intelligence on such threats.”

Another source of confusion surrounding the incident at Fairford has been investigators’ decision to bail the suspects despite their arrests under terror laws and Burnham’s public comments that Iran was likely behind it. Trump criticized that move, saying he wouldn’t have let them go.

British officials stressed that the men had only been released under the tightest of bail conditions and that they remain under investigation. That gave them confidence that there is no ongoing threat from these suspects, they said.

Senator Mark Warner, the top Democrat on the Intelligence Committee, also criticized the Trump administration for giving Iran a rhetorical boost.

“We have to protect our personnel first and foremost, but this kind of hurried exit at least gives Iran a propaganda win that they can claim hey, we chased the Americans out of their closest ally, the British, away from the UK airbase,” Warner said in a Bloomberg TV interview.