President Joe Biden delivered a forceful and highly personal condemnation of Russia's Vladimir Putin on Saturday, summoning a call for liberal democracy and a durable resolve among Western nations in the face of a brutal autocrat.

As he capped a four-day trip to Europe, a blend of emotive scenes with refugees and standing among other world leaders in grand settings, Biden said of Putin: "For God's sake, this man cannot remain in power."

It was a dramatic escalation in rhetoric - Biden had earlier called Putin a "butcher" - that the White House found itself quickly walking back. Before Biden could even board Air Force One to begin the flight back to Washington, aides were clarifying that he wasn't calling for an immediate change in government in Moscow.

Kremlin spokesman Dmitry Peskov quickly denounced Biden, saying "it's not up to the president of the U.S. and not up to the Americans to decide who will remain in power in Russia."

While Biden's blunt language grabbed headlines, in other pieces of his roughly 30-minute speech before Warsaw's iconic Royal Castle he urged Western allies to brace for what will be a turbulent road ahead in a "new battle for freedom."

He also pointedly warned Putin against invading even "an inch" of territory of a NATO nation.

The address was a heavy bookend to a European visit in which Biden met with NATO and other Western leaders, visited the front lines of the growing refugee crisis and even held a young Ukrainian girl in his arms as he sought to spotlight some of the vast tentacles of the conflict that will likely define his presidency.

"We must remain unified today and tomorrow and the day after, and for the years and decades to come. It will not be easy," Biden said as Russia continued to pound several Ukrainian cities. "There will be costs, but the price we have to pay, because the darkness that drives autocracy is ultimately no match for the flame of liberty that lights the souls of free people everywhere."

Biden also made the case that multilateral institutions like NATO are more important than ever if the West and its allies are going to successfully push back against autocrats like Putin.

During his campaign for president, Biden talked often about the battle for primacy between democracies and autocracies. In those moments, his words seemed like an abstraction. Now, they have an urgent resonance.

Europe finds itself ensconced in a crisis that has virtually all of Europe revisiting defense spending, energy policy and more, and so does the U.S.

Charles Kupchan, who served as senior director for European affairs on the White House National Security Council during the Obama administration, called the invasion a "game-changer" that left Atlantic democracies with "no choice" but to bolster their posture against Russia.

But the path ahead for Biden - and the West - will only grow more complicated, Kupchan said.

"The challenges Biden's presidency faces have just grown in magnitude," said Kupchan, now a senior fellow at the Council on Foreign Relations. "He now needs to lead the West's efforts to protect the West from the pressing external threat posed by Russia. And he needs to continue strengthening the West from within by countering the illiberal populism that still poses internal threats to democratic societies on both sides of the Atlantic."

In one of the most poignant moments of his trip, Biden on Saturday bent down and picked up a young girl, a Ukrainian refugee in a pink winter coat, and spoke of how she reminded him of his own granddaughters.

"I don't speak Ukrainian, but tell her I want to take her home," Biden asked a translator to tell the smiling child.

Hours later, Biden was in front of a crowd of a 1,000 - including recent Ukrainian refugees - at the Royal Castle, a Warsaw landmark that dates back more than 400 years and was badly damaged in World War II. He made clear that the West would need to steel itself for what will be a long and difficult battle.

"We must commit now, to be this fight for the long haul," Biden said.

The Biden administration, which has been selective about putting too great of importance on any single policy speech, sought to elevate what White House officials billed as a major address. Biden spoke with grand palace behind him to an invited audience - one bigger than just about any he's spoken to during his presidency.

He singled out Lech Walesa, the Polish labor leader who led the push for freedom in his country and was eventually elected its president, and connected the moment to the former Soviet Union's history of brutal oppression, including the post-World War II military operations to stamp out pro-democracy movements in Hungary, Poland and what was then Czechoslovakia. And he urged Europe to heed the words of Pope John Paul II, the first pontiff from Poland: "Be not afraid."

Biden's trip has reaffirmed the importance of European alliances, which atrophied under former President Donald Trump. He's worked with his counterparts to marshal an array of punishing sanctions on Russia, and placed the continent on a course that could eliminate its dependence on Russian energy over the next several years.

The collective response to the invasion of Ukraine has little parallel in recent history, which has been more characterized by widening divisions than close coordination. But the Russian invasion of Ukraine has changed that dynamic, with European nations stepping up defense spending and imposing crushing sanctions against Moscow, and some taking initial steps to reorient their energy needs away from Russia.

"I'm confident that Vladimir Putin was counting on dividing NATO," Biden said during a meeting with Polish President Andrzej Duda on Friday. "But he hasn't been able to do it. We've all stayed together."

Maintaining such unity will likely prove difficult as the war grinds on, and the refugee situation could become one source of strain. Much like NATO is committed to the collective defense of each member, Biden said, other nations should share the burden of caring for Ukrainian refugees. To that end, the U.S. administration announced it would admit up to 100,000 Ukrainian refugees into the United States this year.

"It should be all of NATO's responsibility," he told Duda, whose country has accepted roughly 2.2 million of the 3.7 million who have fled Ukraine. It's not clear how many of those displaced Ukrainians who have come through Poland have now moved on to other nations.

There's also no clear path to ending the conflict. Although Russian officials have suggested they will focus their invasion on the Donbas, a region in East Ukraine, Biden wasn't so sure if there was a real shift underway.

Asked on Saturday if the Russians have changed their strategy, he told reporters that "I am not sure they have."

Despite the hazards ahead, Biden insisted there is more reason to be hopeful that the West and Ukraine can eventually succeed.

"A dictator bent on rebuilding an empire will never erase a people's love for liberty," Biden said. "Brutality will never grind down their will to be free. Ukraine will never be a victory for Russia, for free people refuse to live in a world of hopelessness and darkness."

From The Associated Press