In remarks outside the Royal Castle in Warsaw, Mr. Biden sought to send a message to Russian President Vladimir Putin that the U.S. and its allies will stand together if he encroaches on NATO territory.
It was the furthest Mr. Biden has gone in calling for a regime change in Russia, reflecting a major turning point in U.S. rhetoric towards Moscow. U.S. officials had previously said their goal was not its goal.
Mr. Biden called Mr. Putin “a dictator,” continuing the escalation of words between the two nations. Earlier Saturday, while meeting with Ukrainian refugees, Mr. Biden called the Russian president “a butcher” and on Friday suggested Mr. Putin met the “legal definition of a war criminal.”
Mr. Biden accused Mr. Putin of strangling democracy at home and seeking to do the same in neighboring nations. He said the conflict could bring about “decades of war.”
He urged Ukrainians to steel themselves for a long battle ahead, while warning Mr. Putin to stay away from NATO territory.
“Don’t even think about moving on a single inch of NATO territory. We have a sacred obligation under Article 5 of defending each and every inch of NATO territory with the full force of our collective power,” Mr. Biden said.
Under Article 5 of the NATO charter, an attack on one member of the alliance must be met with a collective response from all the members.
Mr. Biden said the Russian leader’s actions have drawn NATO closer together than it had been in years, saying Mr. Putin’s “brutal tactics” have strengthened its resolve.
The remarks came just moments after officials in the Ukrainian city of Lviv reported several powerful explosions and large plumes of smoke that could be billowing in the air. Lviv sits about 40 miles from the border of Poland, which is a NATO member.
Casting the Russian invasion of Ukraine as a historic global battle between democracy and autocracy, Mr. Biden urged democracies around the world to unify against such authoritarian aggression.
“In the perennial struggle for democracy and freedom, Ukraine and its people are on the frontlines, fighting to save their nation. Mr. Biden said. “Their brave resistance is part of a larger fight for essential democratic principles that unit all free people.”
Speaking directly to the Russian people, Mr. Biden assured them they “are not our enemy,” seeking to separate civilians from the actions of their leader. He called on Russians, including those who were alive during the Soviet Union, to speak out against its war.
“I refuse to believe that you welcome the killing of innocent children and grandparents or that you accept hospitals, schools, maternity wards — for God’s sake — being pummeled with Russian missiles and bombs,” he said.
“This is not who you are. This is not the future you deserve for your families and your children. I’m telling you the truth. This war is not worthy of you, the Russian people,” Mr. Biden continued.
A portion of Mr. Biden’s remarks were spent calling out Mr. Putin’s lies justifying his invasion of Ukraine. Mr. Putin has claimed the Russian military aggression was necessary to “denazify” Ukraine.
Mr. Biden said his Russian counterpart’s comments were “obscene,” noting that Ukraine President Volodymyr Zelesnkyy is Jewish and his father was killed in the Nazi Holocaust.
“Putin has the gall to say he’s ‘denazifying Ukraine.’ It’s a lie. It’s just cynical. He knows that,” Mr. Biden said.
Turning to the economic sanctions the West has imposed on Russia, Mr. Biden made clear that “Putin is to blame” for the penalties. He said the sanctions are crushing Moscow’s economy and its currency, adding that the Russian ruble has been reduced to “rubble.”
The speech was the culmination of Mr. Biden’s whirlwind trip to Belgium and Poland, which kicked off with meetings with members of the G-7 and NATO. It concluded with Mr. Biden’s meeting with Polish President Andrzej Duda and speaking with Ukrainian refugees.