Terror suspects arrested last week may have been part of a plot to target a US Independence Day celebration at RAF Feltwell, in Norfolk.
The event, which attracts American nationals from across the country, was suddenly cancelled two days before July 4 following a raised security threat level.
Twelve days later three men in their 20s and 30s were arrested - one in Letchworth and the others in Luton.
Scotland Yard said the arrests by its Counter Terrorism Command were part of an ongoing investigation into Islamist-related terrorism.
At the time, a spokeswoman for RAF Feltwell said: “The cancellation was due to an increased security threat level and at this point is in connection to the arrests.”
Today, Junead Ahmed Khan, 24, and Shazib Ahmed Khan, 22, both of Marlow Avenue, Luton, appeared at Westminster Magistrates’ Court where they were charged with being involved in the preparation with the intention to commit acts of terrorism.
They were remanded in custody to appear at London’s Old Bailey on August 10.
A third man, in his 30s, was released without charge yesterday.