Around 60 British troops, including counter-drone specialists, have been deployed to help defend three air bases used by the US Air Force in the UK after a spate of "weird" drone sightings.
The military personnel will also support efforts to find out who is operating the unmanned aerial vehicles amid fears the mysterious sorties might be part of some "coordinated" operation.
It comes after a number of drones were spotted over three air bases in Britain that are used by American military aircraft and personnel.
US military units on Tuesday were still monitoring the airspace over RAF Lakenheath and RAF Mildenhall, in Suffolk, and RAF Feltwell in Norfolk after the unmanned aerial vehicles were sighted overnight, a spokesperson said.
The drones have not been identified as hostile.
The RAF is understood to be working to help check the airspace and ensure the safety of the sites.
"I can confirm the situation is ongoing and our units continue to monitor the airspace and are working with host-nation authorities and mission partners to ensure the safety of base personnel, facilities, and assets," the US Air Forces in Europe spokesperson said.
"To safeguard operational security, we do not discuss specific force protection measures, however we retain the right to protect our installations."
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The development comes after drones were previously spotted between Wednesday and Friday of last week over the same three airbases - a highly unusual occurrence.
These drones were also not identified as hostile. It is understood that the drones have not had any impact on residents or infrastructure at the bases.
The US Air Force at the time said it was unclear whether the drones were considered hostile.
A spokesperson for the Ministry of Defence said: "We take threats seriously and maintain robust measures at defence sites. We are supporting the US Air Force response."
(c) Sky News 2024: British forces deployed after drones spotted again over three US air bases in UK
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