Haven't the Yanks just moved into an RAF base in Norfolk? Maybe them conducting drills.
EDIT: http://www.lakenheath.af.mil/library/factsheets/
Must be Yanks.
F15s are so sexy.
AFAIK, they regularly have 'dummy' bombs on board for training missions.
Unless ISIS found a fighter pilot for their rusty migs, I don't think it's unusual.