A serving US Army soldier has been arrested near Gloucester on suspicion of national security offences involving allegations linked to Russia, in an investigation bringing together British counter-terrorism officers, the FBI and US military authorities.

The 41-year-old man was detained on 10 November on suspicion of offences under Sections 1 and 3 of the National Security Act 2023. Officers are searching two properties in Gloucestershire.

Counter Terrorism Policing London is leading the investigation. Police confirmed that Russia is the country to which the allegations relate, while FBI Director Kash Patel described the case as involving allegations of espionage.

The soldier’s position of trust is central to the concern expressed by US military officials. Brigadier General Sean Stinchon, commanding general of US Army Counterintelligence Command, described him as a senior soldier entrusted with sensitive information. Stinchon said the alleged conduct illustrated the persistent risk of insider threats and urged anyone who witnessed suspicious activity to report it to their local counterintelligence office.

Deputy Assistant Commissioner Vicki Evans, the senior national co-ordinator for Counter Terrorism Policing, emphasised both the seriousness of the allegations and the continuing enquiries. “The allegations are serious and our investigation is very much ongoing,” she said.

Evans said the arrest resulted from close British-American collaboration and that the authorities would act together against suspected criminal activity capable of undermining national security.

Patel likewise stressed the importance of international partnerships, thanking Counter Terrorism Policing, MI5, UK Defence Counter Intelligence and US Army Counterintelligence Command. He said the FBI had made 167 counterintelligence and espionage arrests over the previous 21 months, a 53% increase. Those figures describe broader FBI activity, rather than evidence establishing the allegations in this case.

The investigation remains ongoing. Police said it is not linked to any other current Counter Terrorism Policing investigations.