About 20,000 extra troops were deployed to the region in 2022 under former president Joe Biden, reinforcing NATO's eastern flank after Russia invaded Ukraine.

NBC cited six US and European officials confirming discussions about halving the deployment, focused on cutting numbers in Romania and Poland.

President Donald Trump is pushing for a speedy end to the more than three-year war in Ukraine since taking office but has failed to yet reach a breakthrough.

He has repeatedly criticized NATO, and insisted that Europe take more responsibility for its defense by boosting military spending and taking the lead in arming Ukraine.

Any downsizing of US forces would increase President Vladimir Putin's "willingness to meddle in various ways across the spectrum in Europe," Seth Jones, of the Center for Strategic and International Studies, told NBC.

About 100,000 American troops are currently stationed in Europe, with 65,000 based permanently on the continent, while the rest are rotating staff and reinforcements.