Loud jet planes were heard flying in the air above Swansea at lunchtime on Tuesday, March 8.
Residents across the city and county would have been peering up to the skies due to the recurring sound of noisy jet engines.
According to a flight tracker website it appears as if at least one of the American air force planes set off from RAF Lakenheath in Suffolk, England, before heading directly south west for Swansea.
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It was first heard in the skies at around 1.45pm and was seen on the tracker completing a flat loop shape over Swansea, taking it out into the Bristol Channel and back again.
Most recently the McDonnell Douglas F-15 Eagle was tracked taking a wider circle from Gower over Llanelli and Burry Port.
Did you see or hear the jets? Have your say in the comments below.
The F-15 is said to be a twin-engine, all-weather tactical fighter aircraft with a top speed of 3,018 km/h and a range of 4,815 km.
RAF Lakenheath has been approached for comment.
But the Ministry of Defence said there were also RAF Typhoons operating in Welsh skies today; the USAFE F-15s having left RAF Lakenheath, and the Typhoons from RAF Coningsby.
A spokesman said: "Typhoon fighters from RAF Coningsby, Lincolnshire, were completing a variety of routine air-to-air and air to ground training in Wales and south west England today.
"The RAF and in this case, Typhoon pilots, use a variety of training areas around the whole of the UK for training and vary their routes and training locations to maximise training benefit; recently our aircraft have been training across large parts of Scotland, Wales, North East England, the North Sea, Norfolk, the north west, Liverpool, the south coast and Isle of Wight.
"Use of such training areas enable RAF pilots to train in varied environments in preparation for operations across the globe, such as those ongoing in the Middle East and eastern Europe.
"The RAF Typhoon force continues to be on high readiness to deploy around the world in support of operations – an example is the recent deployment of additional aircraft to Cyprus to patrol NATO / Romanian airspace post-Russian aggression in Ukraine".
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