Two British men have been charged with national security offences in connection with a suspected plot targeting RAF Fairford, a US-operated military air base in western England that has been used by American bombers to strike Iran.Mohmed Ahmad Abdulkarim and Nouman Essghir, both 24 and residents of London, were charged under the National Security Act, the Crown Prosecution Service said on Tuesday. They are expected to appear in court later in the day.Abdulkarim faces a charge of assisting Iran’s intelligence service, while Essghir has been accused of entering a prohibited site for a purpose prejudicial to the UK.Suspected plot led to evacuationsEssghir was arrested outside RAF Fairford on September 27, prompting a major security operation involving armed police and army bomb-disposal experts. Scores of residents were evacuated from nearby homes as authorities searched for explosives.Police later said they had discovered gasoline, an accelerant, in vans at the scene but had found no explosives.Essghir was initially released on bail before being arrested again last week. Abdulkarim was also arrested in the past week. Six other men have been arrested and released on bail as the investigation continues.The incident prompted US authorities to withdraw their bombers from RAF Fairford amid concerns over a potential Iranian-linked threat.British authorities have linked Tehran to the suspected plot. Prime Minister Andy Burnham said the incident was “almost certainly” directed by Iran’s Revolutionary Guard. Iran has denied involvement, though it has previously maintained that military bases used to attack its territory could be considered legitimate targets.MI5 warns of rising Iran-linked threatsThe arrests come amid warnings from British intelligence officials about an increase in threats linked to foreign states.Earlier this month, MI5 director general Ken McCallum warned that Iran and Russia were expanding their hostile activities in the UK. He said Tehran was seeking to widen its targets beyond Iranians opposed to the country’s Islamic authorities.McCallum said more than 50 people had been arrested over Iran-linked plots in the past year.Laurence Taylor, assistant commissioner and head of National Counter Terrorism Policing in the UK, said authorities were working to identify and counter threats believed to be directed by Iran.“We have seen a range of incidents in recent months that we believe have been directed by the Iranian state,” Taylor said, adding that authorities were working together to respond to the threat.