Polish leaders declared themselves alone no longer at a ceremony Saturday welcoming the arrival of U.S. troops as part of a deployment that has angered Russia.

The presence of U.S. troops on Polish soil marks a historic moment—the first time Western forces are being deployed on a continuous basis to bolster NATO’s eastern flank.

“"We have waited for you for a very long time,” the soliders heard Defense Minister Antoni Macierewicz say at Saturday’s event in Zagan amid falling snow. “We waited for decades, sometimes feeling we had been left alone, sometimes almost losing hope, sometimes feeling that we were the only one who protected civilization from aggression that came from the east.”

The event also drew hundreds of ordinary Poles.

The American deployment includes an armored brigade of 3,500 American troops from Fort Carson, Colorado. It comes in reactions to Russia's annexation of Crimea from Ukraine in 2014 and its backing of separatist insurgents in Ukraine's east.

Those actions have frightened many in Poland, the Baltic states and other countries in Eastern Europe that were once under Moscow's control.

“This is America's most capable fighting force: a combat-ready, highly trained US armoured brigade, with our most advanced equipment and weaponry,” U.S. ambassador to Poland Paul James said at the ceremonies, according to an AFP report.

"This force embodies America's iron-clad commitment to honor our NATO treaty obligation to defend our NATO allies."

The Polish government organized several other events across the country, including in downtown Warsaw, to welcome the Americans.

“This is an important day for Poland, for Europe, for our common defense,” Prime Minister Beata Szydlo told the U.S. soldiers.

The troops are due to fan out across seven countries from Estonia to Bulgaria for exercises. A headquarters unit will be stationed in Germany. After nine months they will be replaced by another unit.

NATO will also deploy four multinational battalions to its eastern flank later this year, one each to Poland and the three Baltic states. The U.S. will also lead one of those battalions.

The Kremlin has denounced all these deployments, saying it considers them a threat to its own security and interests.

One of the newly arrived Americans M.P Peter Gomez told AFP he felt “very welcome” as he posed for selfies with Polish citizens.

“I'm surprised actually,” he was quoted as saying. “People are very excited to see us.”

The Associated Press contributed to this report.