An image purporting to show the moment five men were arrested was sent to the .
It showed detained men in Whelford, about 350m (1,148ft) from runway access at Crash Gate 6A at RAF Fairford.
The has been unable to verify the original source, but Verify has geolocated the image and confirmed it appeared to be authentic.
The base shares a long history with the American military, and has recently been used by US warplanes as a staging post for defensive strikes on Iran.
US President Donald Trump said those arrested had been “looking to do big damage”, adding: “We had them under view for a long time, and we got them.”
UK Defence Secretary Wes Streeting said he had been in contact with his US counterpart, Pete Hegseth.
A USAF spokesperson said its personnel remained vigilant but did not discuss specific force protection methods.
The US Department of Defense meanwhile raised the threat level at RAF Lakenheath in Suffolk – which hosts the USAF’s 48th Fighter Wing – to its second-highest category.