Two men have been charged with offences under the UK's National Security Act following an incident in September at RAF Fairford, an airbase used by the US to strike Iran.
Mohmed Abdulkarim, 24, has been charged with assisting a foreign intelligence service, while Nouman Essghir, 24, was charged with one offence of entering a prohibited place for a purpose prejudicial to the UK.
Assistant Commissioner Laurence Taylor, Head of National Counter Terrorism Policing in the UK, said police believed the country Abdulkarim was assisting was Iran.
The US removed its bombers from the base on security grounds shortly after five British men were arrested outside the military base in southwest England in the early hours of September 27.
A 25-year-old UK-Iranian national, who was re-arrested last week, has been released without charge but remains on police bail following his initial arrest earlier this month, counter-terror police have said.
A major incident was declared after three suspicious vehicles were seen near the US-operated airbase in Gloucestershire on 27 September.