British prosecutors said Tuesday that two men had been charged under the National Security Act in connection with a September incident near RAF Fairford, an airbase used by US forces to launch strikes on Iran.
US bombers were withdrawn from Fairford on security grounds shortly after arrests immediately after the incident.
What have police said about the Fairford suspects?
The Crown Prosecution Service charged Mohmed A., a 24-year-old British-Iranian dual national, with engaging in conduct likely to materially assist a foreign intelligence service. Counterterrorism police chief Laurence Taylor said investigators believed the country involved was Iran.
Nouman E., a 24-year-old British citizen, was charged with entering a prohibited place for a purpose prejudicial to the UK on August 22. Both men were due to appear in court later Tuesday.
The investigation began after armed police responded to reports of three suspicious vehicles near the Gloucestershire base on September 27 and arrested five men. Seven men have been arrested during the inquiry.
Scores of residents were evacuated as police and military bomb-disposal experts searched the area for explosives.
Police have said they consider Iranian state involvement "highly likely." Two suspects were rearrested on October 20 on suspicion of assisting a foreign intelligence service.
Iran has denied involvement, although it has previously said it considers bases used to attack its territory legitimate targets.
This is a developing news story that will be updated...