Two Latvian men were arrested for breaching the perimeter fence at RAF Molesworth in Cambridgeshire. Police are investigating whether Russia was behind the break-in.
At around 10pm on Wednesday, Ministry of Defence security patrols discovered an abandoned vehicle close to the base's perimeter. Subsequent searches uncovered a small hole in the perimeter fence.
Two Latvian men, aged 36 and 32, who are based in the UK, were then found inside the grounds and initially detained on suspicion of trespassing on a prohibited site and criminal damage.
Arrest under National Security Act
They were later arrested on suspicion of an offence under Section 4 of the National Security Act 2023, which relates to entering a prohibited place for a purpose prejudicial to the UK.
Specialist explosive ordnance disposal officers were called in to examine the abandoned vehicle for any possible traces of explosives, amid security concerns.
RAF Fairford incident not linked
Officers said the security breach was not being linked to the investigation into RAF Fairford, where last month five men were arrested near the base. A police cordon was stood down after nothing suspicious was found.
RAF Molesworth serves as a base for American intelligence operations covering Europe and Africa and as a NATO intelligence hub. According to the NATO website, a conference on Russia was held there on Tuesday and Wednesday.
Investigation ongoing
Commander Helen Flanagan, head of Counter Terrorism Policing London, said: "We're very aware of the recent heightened interest and concern around military sites, but at this stage there is nothing to suggest this incident is connected to the events at RAF Fairford last week."
"Our investigation into this incident is at its very early stages," she added. "A big part of this is looking at any potential motivation as to why the men were present at the site, but I must stress we are keeping an open mind at this stage and inquiries are very much ongoing."
Searches at two addresses in the Peterborough area are being carried out in connection with the investigation.
