Five men were arrested in the operation on Sunday on suspicion of planning a terrorist attack against the air base RAF Fairford, which is used by both the UK and the US.
The men, all British citizens aged 20-25, were released on bail on Monday.
Laurence Taylor, head of British counter-terrorism police, emphasises that the men are “definitely still the subject of investigation.”
Release causes confusion
The fact that the men were released after such a short time, in a case with such serious suspicions, has caused confusion.
"I understand that this development came as a surprise to some, but I want to emphasise that this is an investigative decision based on experience and strategy," Taylor said, according to the AP news agency.
The police chief adds that people's concerns about the incident are “reinforced by the international comments we see.”
Both US President Donald Trump and US Secretary of State Marco Rubio have said in repeated interviews that a “foreign actor” was involved and that it was a foiled terror plot. Trump has said it “may be” linked to Iran.
Denies involvement
Iran has denied involvement. Trump is critical of the suspects being released on bail.
I'm surprised they released them, I wouldn't have done it, Trump says, adding that British authorities worked closely with the United States.
We know everything about them. We wouldn't have let them go.
The base has been used by American bombers during decades of conflicts in the Middle East, including this year's war against Iran.
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