Poland's leaders are set to stage a formal welcome ceremony Saturday for the biggest US troop deployment to Europe in decades.

Some 4,000 US soldiers have been deployed as part of troop rotations to Europe that the Pentagon has said are intended to bolster ties with NATO allies and send a clear message to Russia.

Russia has criticized the continuous deployments as "a threat" to Russian security.

Polish Prime Minister Beata Szydlo and Defense Minister Antoni Macierewicz are expected to attend Saturday's event in the Polish town of Zagan.

A convoy of US troops and military equipment crossed the border into Poland on Thursday, having arrived in the German city of Bremerhaven on Sunday.

After assembling in Poland, the 3rd Armored Combat Brigade Team of the 4th Infantry Division, deployed from Fort Carson, Colorado, will disperse across seven locations in Eastern Europe for training and exercises with European allies.

It will serve as part of a rotation of American military assets in the region and is part of an effort to demonstrate America's "rock solid" commitment to its European allies in the wake of Russian President Vladimir Putin's intervention in Ukraine, according to US European Command Deputy Commander Lt. Gen. Tim Ray.

Deploying the troops and military hardware is the latest in a series of moves by the US to ramp up its land, sea and air presence in Europe, against a backdrop of concern over potential Russian aggression.

(Source: CNN)