People faced a "noisy" evening as a fighter jet flew backwards and forwards across Norfolk overnight.
The US Air Force Boeing F-15 E Strike Eagle launched from RAF Lakenheath at about 8.15pm on Tuesday (August 16).
Within minutes it had roared across the county over Dereham, Norwich and the Broads before heading out into the North Sea.
It continued to go back and forth across the county several times for almost two hours before returning to its base in Brandon, Suffolk, at about 10pm.
Zena Leech-Calton, who lives west of Norwich, said: "We could hear them going for a while. It was very noisy and it seems half of Norwich was wondering what was going on after seeing all the messages online.
"In a positive way it is good that we have these American jets nearby, it's reassuring that we'd have that protection."
Both F-15E and F-35A fighter jets have been conducting night flying training this week, which is expected to continue for one more day until Thursday, August 18.
The jet rose to over 22,000ft in the sky and travelled at a speed of over 600 knots.
One person living in the NR3 area said: "At first I thought it was thunder but it was so loud I thought it must be something else.
"It lasted for ages and sounded like something out of War of the Worlds."
A spokesman for RAF Lakenheath said: "Communities in East Anglia and the surrounding regions may see or hear U.S. aircraft taking off, landing and transiting between RAF Lakenheath and training ranges over the North Sea between 7pm and 10.30pm.
"Overland flying will be limited as much as possible between sunset and sunrise.
"Exercises like this provide both aircrew and support personnel stationed at RAF Lakenheath the experience needed to maintain a ready force capable of ensuring the collective defence of the NATO alliance and mutual security agreements between the US and UK.
"The exercise does not include plans for low-altitude flying in East Anglia or the surrounding regions. All training will be conducted in accordance with Ministry of Defence and U.K. airspace regulations."
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