President Joe Biden wrapped up a whirlwind, four-day visit to Poland and Ukraine on Wednesday by reassuring eastern flank NATO allies that his administration is highly attuned to the looming threats and other impacts spurred by the grinding Russian invasion of Ukraine.

Before departing Warsaw, Biden held talks with leaders from the Bucharest Nine, a collection of nations on the most eastern parts of the NATO alliance that came together in response to Russian President Vladimir Putin’s 2014 annexation of Crimea from Ukraine.

As the war in Ukraine drags on, the Bucharest Nine countries’ anxieties have remained heightened. Many worry Putin could move to take military action against them next if he’s successful in Ukraine. The alliance includes Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania and Slovakia.

The meeting took place two days before the one-year anniversary of Russia’s invasion of Ukraine.

“As NATO’s eastern flank, you’re the front lines of our collective defense, and you know better than anyone what’s at stake in this conflict, not just for Ukraine, but for the freedom of democracies throughout Europe and around the world,” Biden said in remarks that were open to the press.

Biden touted the billions of dollars in military and humanitarian aid that the United States has allocated to Ukraine and reiterated that “we’ll continue our enduring support for Ukraine as they defend their freedom.”

The White House said in a statement after the meeting that the leaders “reaffirmed their unwavering support for Ukraine and underscored their shared commitment to stand with the Ukrainian people for as long as it takes. They discussed the strengthened defensive posture on NATO’s eastern flank, and President Biden reiterated the United States’ ironclad commitment to NATO’s Article 5,” which states that an armed attacked against any NATO nation shall be considered an attack on all 30.

"One of the things that Putin was counting on was that there would be division and lack of resolve in the West, and that he could fracture or create disagreements between the Americans and the Europeans are within the alliance," Jeffrey Pryce, a Senior Fellow at the Foreign Policy Institute at the Johns Hopkins School of Advanced International Studies, told Spectrum News. "And what you saw instead was incredible unity on both sides of the Atlantic."

Pryce, a former Pentagon official, said that Biden's trip came at a critical time, ahead of the one-year anniversary of Russia's invasion of Ukraine. 

"I think it is really important for reassuring the allies, in particular the Eastern Flank of NATO and obviously Kyiv, and getting a real shot in the arm to the Ukrainian people as they're resisting this aggression," Pryce told Spectrum News.

NATO Secretary-General Jens Stoltenberg, who attended the meeting, said Russia’s “pattern of aggression” began in 2008 in Georgia, moved into regions of Ukraine in 2014 and then became a full-fledged invasion of its neighbor last year. 

“We cannot allow Russia to continue to chip away at European security,” Stoltenberg said. “We must break the cycle of Russian aggression.”

Stoltenberg added that after one year, Putin “is not preparing for peace. On the contrary, he is preparing for more war.”

B9 leaders who spoke during the public portion of the meeting called for continued commitment to supporting Ukraine.

“To make sure that this brutal war against Ukraine is Russia’s final act, we also must be resolute in deterring further aggression and rolling back the current one,” said Romanian President Klaus Iohannis.

The White House has praised several eastern flank countries, including Lithuania, Poland and Romania, over the last year for stepping up efforts to back Ukraine with weapons and economic aid and taking in refugees.

Biden has given particular attention to Poland’s efforts. The country is hosting about 1.5 million Ukrainian refugees and has committed $3.8 billion in military and economic aide to Kyiv.

“The truth of the matter is: The United States needs Poland and NATO as much as NATO needs the United States,” Biden said during talks Tuesday with Polish President Andrzej Duda.

Addressing concerns of the NATO members that they could be next, Biden pledged during a speech in Warsaw on Tuesday America’s ironclad commitment to the mutual-defense treaty and Ukraine’s defense.

“Appetites of the autocrat cannot be appeased,” he said. “They must be opposed.”

Hungarian Prime Minister Viktor Orban, the right-wing populist leader who argued last week that the European Union is partly to blame for prolonging Russia’s war in Ukraine, has balked at sanctions on Moscow and arming Kyiv.

Orban skipped Wednesday’s meeting with Biden, sending President Katalin Novák in his place.

After the meeting, Biden headed to the airport to fly back to Washington.