MOSCOW • The Kremlin said yesterday it was concerned by what it described as a US military build-up in Poland, saying the move represented a threat to its national security.

US troops and tanks began arriving in Poland yesterday, part of one of the largest deployments of US forces in Europe since the Cold War that will eventually involve more than 3,000 soldiers.

Addressing reporters on a conference call, Kremlin spokesman Dmitry Peskov said Russia regarded the move as an aggressive step along its borders.

"This operation threatens our interests and our security," he said. "This is even more pronounced when a third party (the United States) reinforces its military presence on our doorstep in Europe."

Russian Deputy Foreign Minister Alexei Mechkov described the deployment as a "factor destabilising European security".

The Atlantic Resolve mission will see an armoured brigade with more than 3,000 American soldiers and heavy equipment deployed in Poland and nearby Nato partners Estonia, Latvia, Lithuania, Romania, Bulgaria and Hungary on a rotational basis.

A contingent of US troops entered Poland at the Olszyna border crossing with Germany yesterday. Heavy equipment, including 87 Abrams tanks and more than 500 personnel carriers, including military- equipped Humvees, were to follow.

The outgoing Obama administration ordered the deployment in 2014 to reassure eastern allies after Russia's actions in Ukraine. But the operation comes a week ahead of the inauguration of US President-elect Donald Trump, who has suggested his Republican administration will seek to ease tensions with the Kremlin.

Last summer, Nato leaders also endorsed plans to rotate troops into Poland and the three Baltic states to reassure them they would not be left in the lurch if Russia was tempted to repeat its 2014 Ukraine intervention.

A separate US-led battalion working within the Nato framework will be stationed near Poland's north- east border with Russia's Kaliningrad exclave.

Mr Peskov also said yesterday that the Kremlin did not agree with views on Crimea expressed by US Secretary of State nominee Rex Tillerson at a Senate confirmation hearing on Wednesday, where Mr Tillerson said Moscow's 2014 annexation of the Ukrainian peninsula was illegal. Mr Tillerson staked out his turf early in the hearing, arguing that if he had been in office when Russia annexed Crimea in 2014, he would have recommended that the US provide arms and intelligence support to the government of Ukraine, even though it is not a member of Nato.

"What the Russian leadership would have understood is a powerful response," he said, casting the Obama administration's reaction as too weak.

His message to the Russian leadership, he said, would be: "Yes, you took Crimea, but this stops right here."

REUTERS, AGENCE FRANCE-PRESSE, NYTIMES