Warsaw - President Joe Biden spoke out against Russian President Vladimir Putin's decision to suspend his country's participation in the New START nuclear arms control treaty, calling it a "big mistake." The announcement was made as Biden was in Poland, meeting with NATO allies and reassuring them of the United States' commitment to their security amidst the ongoing conflict in Ukraine.

Biden's comments came at the end of a four-day visit to Poland and Ukraine, during which he met with leaders from the Bucharest Nine, a group of countries in the easternmost parts of the NATO alliance. These countries came together in response to Russia's 2014 annexation of Crimea from Ukraine, and as the war in Ukraine continues, their anxieties have remained high.

Biden praised the Bucharest Nine, calling them the "frontlines of our collective defense," and pledged to defend "literally every inch of NATO." He also warned that Russian aggression, if left unchecked, would not stop at Ukraine's borders, saying that "the appetites of the autocrat cannot be appeased; they must be opposed."

The meeting with the Bucharest Nine came a day after Biden marked the one-year anniversary of Russia's invasion of Ukraine at the foot of Warsaw's Royal Castle. He warned that Russian aggression could spread beyond Ukraine and insisted that NATO's mutual-defense pact is "sacred." He also praised several eastern flank countries, including Lithuania, Poland, and Romania, for their efforts to back Ukraine with weapons and economic aid and taking in refugees.

Biden's visit to Ukraine was a grand gesture of solidarity with the country, which has been fighting against Russian aggression for nearly a year. During his visit, Biden gave a speech affirming Europe's role in helping Ukraine repel Russia's ongoing invasion and issued a sharp warning to Putin that the U.S. would not tolerate Moscow defeating Ukraine.

In addition to meeting with Ukrainian officials, Biden also met with Moldovan President Maia Sandu, who last week claimed that Moscow was behind a plot to overthrow her country's government using external saboteurs. Moldova, a former Soviet republic, has sought to forge closer ties with its Western partners since Russia invaded Ukraine nearly a year ago. Biden endorsed Moldova's bid to join the EU and spoke out in support of its "freedom-loving people."

NATO Secretary General Jens Stoltenberg, who was also in attendance at the Bucharest Nine meeting, emphasized the importance of breaking the cycle of Russian aggression, citing past Russian actions in Georgia and Ukraine. He warned that "we cannot allow Russia to continue to chip away at European security."

While several eastern flank countries have stepped up their efforts to support Ukraine, there has been some pushback from other leaders in the region. Hungarian Prime Minister Viktor Orban, for example, has balked at sanctions on Moscow and arming Kyiv. Orban did not attend the meeting with Biden, but Romanian President Klaus Iohannis insisted that "The B9 is stronger than ever."

Biden's trip to Poland and Ukraine was an important show of support for the countries on the front lines of Russian aggression. The ongoing conflict in Ukraine remains a major challenge for the international community, and it is clear that the United States and its allies are committed to standing by their NATO partners and defending the principles of democracy and freedom.