Paratroopers from the US army's 82nd Airborne Division based in Fort Bragg in the United States landed at around 1300 GMT at Rzeszow Airport in southeast Poland on a US Air Force Boeing C-17.

The extra troops "are here to enhance the readiness, interoperability across all domains with our Polish allies and, if necessary, defend any portion of NATO," the division's commanding general Chris Donahue told reporters at the airport.

"Obviously, during this period of uncertainty we know that we are stronger together."

"This deployment is a prudent measure to ensure collectively the prevention of any war aims. It is defensive in nature," Donahue said.

The US last week announced the deployment of 3,000 additional US soldiers to Germany and Eastern Europe as part of efforts to push Russia into withdrawing troops massed on Ukraine's border.

Polish Defence Minister Mariusz Blaszczak said the additional US contingent of 1,700 soldiers would be based "in southeast Poland on NATO's eastern flank".

Poland, a former Communist bloc country which borders Ukraine and joined NATO in 1999, already hosts around 4,500 US troops on rotation.

Preparations for the latest arrivals have been ongoing since last week, and some soldiers landed on Saturday.

Blaszczak said there would be more arrivals "in the coming hours".

The US has also said it is putting 8,500 troops on "heightened" alert for potential deployment in case the NATO Response Force is activated in response to the Ukraine crisis.

The West accuses Russia of preparing for a possible invasion of Ukraine by amassing more than 100,000 troops around the country.

Moscow has denied this, saying only it wants to ensure its own security and accusing NATO of belligerent behaviour.

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BOEING