Part of RAF Mildenhall was evacuated yesterday afternoon when a training bomb was dug up.
Announcements on the base website and Facebook page warn personnel not to approach six buildings, including a petrol station.
A base spokesman said: “100th Security Forces Squadron personnel activated special control measures at approximately 2.50pm after the discovery of an unknown object during excavation clearing, according to Lt Col Kevin Parker of 100th Civil Engineer Squadron commander.
“All security measures were in place to ensure the safety of individuals until officials determined that the object was a training aid designed to simulate an explosive ordinance.
“Safety is a priority of all residents and base population in the area and the base worked closely in conjunction with our local community emergency response partners to access and respond to the situation quickly and safely.”
Suffolk Police said RAF Mildenhall had informed them because it was close to the base boundary, but the incident was entirely dealt with on the base.