A U.K. probe into a suspected bomb plot at a U.S. airbase was mired in confusion Tuesday after media reported no explosives were found in nearby seized vehicles.
As armed guards maintained a cordon around a nearby village, Washington questioned the decision to release on bail five men arrested near the Royal Air Force Fairford base in southwest England.
Three white vans were discovered near the base Sunday and the men – all London-based Britons in their mid-20s – were detained.
Armed police were also visible Tuesday patrolling around the airfield used by U.S. planes to bomb some targets in Iran.
Police have said officers conducted an extensive examination of the vehicles with the help of "military assets" and forensic experts.
They did not disclose their findings. But The Times newspaper and a few other U.K. media have reported that police found no traces of explosives, easing fears that an attack had been foiled but leaving many questions unanswered.
A resident in the neighboring village of Kempsford, Patricia, 60, told AFP it was "very embarrassing that people around the world thought it was a terrorist attack but in the end no – it's a lot of noise for nothing."
Announcing the release Monday of the five suspects, the head of U.K. Counter Terrorism Policing, Assistant Commissioner Laurence Taylor, said the men "absolutely remain under investigation."
He insisted his officers were keeping an "open mind" and considering "every possible angle" in the security scare, including the possible role of "proxies" working knowingly or unknowingly for a foreign state.
Iran's embassy in London has said it "categorically rejects and strongly condemns" speculation that Tehran was involved.
'Serious situation'
Adding to the hazy picture, U.S. President Donald Trump told reporters Monday he was "surprised" that British police had released the five, adding: "I wouldn't have done that."
Hours later, U.S. Secretary of State Marco Rubio called the incident "a very serious situation ... that clearly involves the hand of a foreign actor" but declined to provide further details.
On Sunday, Trump had said the U.K. and U.S. were investigating the suspects "for a long time" and that they "were looking to do big damage to our fort."
The security scare became public after a farmer living in the village of Whelford near the airbase rang police after seeing the three vans blocking a road and a group of masked men fleeing the scene.
Armed officers arrested the five men on suspicion of explosives offenses and, later, "suspicion of preparing a terrorist act" under anti-terror laws.
Security at the base had reportedly been heightened recently.
Britain gave Washington permission in March to use Fairford for "specific defensive operations into Iran" to destroy Iranian missiles at source.
U.S. bombers and other planes have since been seen taking off and landing from the base – the only one on Britain's mainland used for this purpose.
The lack of clarity over the weekend incident has sparked different unverified theories, with some media reporting allegations that the men could even be fuel thieves.
"It's a bit odd they were here in the middle of the night," one local told AFP as she did some gardening in the nearby village of Kempsford.
"If they were true terrorists they wouldn't have released them," she added, asking not to give her name.
Aerial footage of the vans showed they appeared to contain barrels, and at least one was marked with a fake logo and phone number giving the false impression that it was owned by a legitimate diesel delivery firm.
The legitimate firm said in a statement on its website that "neither the vehicle nor any of the individuals involved has any connection whatsoever with Fuel2U," adding it was cooperating with the police.