Planes from RAF Mildenhall are flying near Ukrainian airspace, after Russia launched a "full-scale" invasion on the country.
The planes have been spotted flying around Ukraine on the flight tracking website Flightradar24.
A spokesman for USAFE said US forces were ready to support NATO missions and contingency operations regarding Ukraine.
F-35 Lightning fighter jets were deployed to the Baltic Sea, near Ukraine, while B-52 Stratofortress bombers flew missions with Swedish and Polish forces in the region.
Meanwhile, Stratotanker refuelling aircraft from RAF Mildenhall flew over eastern Europe.
The spokesman said: "US Air Force installations through Europe are postured to support a variety of NATO missions and contingency operations regarding Ukraine.
"RAF Mildenhall and all of our British bases execute a variety of missions, which support the defence of Europe.
"RAF Mildenhall’s refuelling platforms are providing critical refuelling support to all aerial assets moving throughout the theatre in support of contingency and routine operations."
General Jeff Harrigian said: "We are facing a dynamic environment, and the deployment of F-35s to NATO’s eastern flank enhances our defensive posture and amplifies the Alliance’s interoperability.”
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