Originally Published: 21 FEB 23 00:13 ET

Updated: 21 FEB 23 08:42 ET

By Kevin Liptak, CNN

(CNN) -- The last time President Joe Biden spoke from the courtyard of the Royal Castle in Poland, the content of his 27-minute speech was mostly obscured by what he ad-libbed about Russian President Vladimir Putin at the end.

"For God's sake," he proclaimed, "this man cannot remain in power."

Nearly a year later, Biden returns to the Royal Castle this week to mark the anniversary of a war that has increasingly put him directly at odds with the Russian leader, a Cold War dynamic underscored by Biden's highly secretive visit to Kyiv a day earlier.

Standing alongside Ukrainian President Volodymyr Zelensky, Biden used his very presence in the Ukrainian capital to taunt Putin for failing in his ambitions to invade and control the country.

"Putin's war of conquest is failing," Biden said, adding later: "He thought he could outlast us. I don't think he's thinking that right now."

If there was ever a point when Biden and his aides hoped to avoid personalizing the Ukraine conflict, it was over long before this week's anniversary. Biden has declared Putin a "war criminal" and a "pure thug," accusing Russia of genocide and, in his castle speech, making an implicit call for regime change.

Yet this week's carefully planned choreography is striking nonetheless in its overt pitting of Biden against his counterpart in the Kremlin. On Tuesday, each will again engage in a remote rhetorical contest, delivering important speeches to mark one year since Russia launched its invasion.

From the Warsaw castle, Biden intends to recommit to supporting Ukraine, even as the costs mount and public support appears to wane. And in Moscow, Putin delivered a major speech to the Federal Assembly, again falsely claiming that Ukraine and its allies in the West started the war and offering no signs he is pulling back in his ambitions.

Speaking to reporters ahead of Biden's speech, US national security adviser Jake Sullivan described the Warsaw address as an "affirmative statement of values" that would set the Ukraine conflict into a larger context. He said it was not planned as a direct rebuttal to Putin.

"We did not set the speech up some kind of head to head," Sullivan said. "This is not a rhetorical contest with anyone else."

Sullivan said Biden's speech would be bigger than a single response to the address from his counterpart in Moscow.

"The president's remarks today are ... about something larger. And we selected this time, we selected this date, not because President Putin was speaking today," he said.

According to senior US and European officials, Putin's aims have not changed since he launched his invasion a year ago. Despite humiliating setbacks for his military and an apparent power struggle between the mercenary Wagner Group and the Russian defense ministry, Russia has recently made gains in the east. Putin's troops appear poised to take the city of Bakhmut, the first significant Russian military victory in months.

Unlike Biden's last appearance in Warsaw, which came as Putin's forces appeared in retreat and observers expected the Russian economy to crumble under the weight of Western sanctions, the war now appears poised to stretch at least another year. There are currently no serious efforts at negotiating an end to the fighting.

Visiting the region this week, Biden hopes to again provide a rallying cry for Ukraine, demonstrating to Putin and Russia that Western resolve isn't weakening. In meetings with Poland's President Andrzej Duda and other eastern European allies, he reiterated his commitment to those countries' security.

Biden thanked Duda for his country's commitment to supporting the people of Ukraine, calling the relationship between the two nations "critical, critical, critical." Biden said he believes Ukraine is in a "better position than we've ever been" and called on NATO countries to "keep our head and our focus."

"I made it clear that the commitment of the United States is real and that a year later I would argue NATO is stronger than it's ever been," Biden said.

"I can proudly say that our support for Ukraine remains unwavering."

Biden announced Monday he would join European nations in announcing new sanctions on Moscow and unveil another security assistance package on top of the tens of billions already committed this year.

The White House said ahead of his trip that Biden would speak by phone over the course of the week with other Western leaders, including Prime Minister Rishi Sunak of the United Kingdom and President Emmanuel Macron of France.

"Freedom is priceless. It's worth fighting for, for as long as it takes. And that's how long we're going to be with you, Mr. President -- for as long as it takes," Biden told Zelensky in Kyiv on Monday.

The upcoming fight

Yet Biden -- nor any other Western leader -- has not been able to say exactly how long that will be, making this week as much about the year ahead as it is about the past 12 months.

The war has left an indelible mark on nearly all aspects of Biden's presidency and he has left his mark on the war, from the billions of dollars in arms shipments to the newly invigorated Western alliance. It has caused convulsions in the global economy and created political problems at home while still providing Biden an opening to demonstrate his oft-recited claim that "America is back."

White House officials have been looking towards this week's anniversary for weeks, consistently making the point that one year ago, as Russian troops were massing on the border with Ukraine, there were plenty of people -- including inside the Biden administration -- who predicted Kyiv would fall in a matter of days.

The surprising resilience of the Ukrainian people, along with the unexpected ineptitude of the Russian forces, have prevented a full takeover. Instead, the war has become what NATO's chief Jens Stoltenberg described last week as a "grinding war of attrition" without a discernible end.

"I think it is wise to be prepared for a long war," German Chancellor Olaf Scholz, who will visit Biden at the White House early next month, told CNN's Christiane Amanpour on Friday.

The United States and other Western nations have been shipping tranches of arms, tanks and ammunition to Ukraine, steadily increasing what they are willing to provide in the hopes of changing the trajectory of the war. It's not enough for Zelensky, who wants heavier weapons and fighter jets.

US officials have said they hope the massive influx of weaponry to Ukraine -- which includes new vehicles, longer-range missiles, and Patriot air defense systems -- can help Ukraine prevail on the battlefield and put the country in a stronger position to negotiate an end to the war.

But it remains unclear what parameters Zelensky might be willing to accept in any peace negotiations, and the US has steadfastly refused to define what a settlement may look like beyond stating it will be up to Zelensky to decide.

Worries over the future of the war

Meanwhile, new concerns about the available supplies of ammunition and weapons have emerged in the past week, a clear indication the West cannot provide unlimited support forever -- neither logistically nor politically -- as evidenced by polls showing support for the war effort waning.

In the US, some conservative Republicans have balked at providing any more aid to Ukraine, though the party's leaders appear unwavering in their support. As Biden prepares to announce his intentions on running for reelection, anxiety is rising in Europe that a change in the White House could herald a shift in policy toward Ukraine.

"I do have to say that there is a concern, both in Poland and in Ukraine, about the staying power of the US beyond this administration. This war would look entirely different without the support of the US," said Michal Baranowski, the managing director in Warsaw of the German Marshall Fund.

"The fact is that we are fighting with time, right?" Baranowski said. "I mean, it's really whether time is on the side of Russia, who is losing but has a lot of resources to deplete us in the West. That's what gives me pause. I hope we have the staying power."

White House officials said that in Biden's upcoming speech from Warsaw's castle marking the anniversary of the war, the president plans to speak to the costs the war has inflicted on the rest of the world. He and his aides have sought to downplay the prospect Republicans might sharply reduce American aid to Ukraine, noting GOP leaders are largely aligned in their support.

In an indication of the massive number of refugees Poland has absorbed since the start of the war, his remarks will be translated into both Polish and Ukrainian.

John Kirby, the strategic communications coordinator at the National Security Council, said the president's message would be for "people all around the world."

But nearly a year after calling for his ouster from the same location, Biden also plans to convey a message to the man in the Kremlin.

"You'll hear him messaging Mr. Putin as well as the Russian people," Kirby said.