Suffolk police say a 44-year-old man arrested in connection with an incident at the US airforce base at RAF Mildenhall on Monday has been detained under section 136 of the Mental Health Act.
The British man was arrested on suspicion of criminal trespass and criminal damage.
Shots were fired by US service personnel and the airfield put on lockdown after reports of a disturbance.
Superintendent Kim Warner, of Suffolk Police, said a vehicle failed to follow security directions at the entrance and drove on to the base.
There was a "short pursuit" and the vehicle was stopped by US security services, he said.
Shots were fired by US service personnel and a man has been detained after a disturbance at RAF Mildenhall, Suffolk Police said.
Police in Suffolk have confirmed they're dealing with a "significant incident" at RAF Mildenhall.