Joe Biden visits Poland following Ukraine visit.

President Joe Biden arrived in Poland by train following his surprise visit to Kyiv, Ukraine, days before the one-year anniversary of Russia’s invasion. During his two-day stay in Warsaw, Biden is scheduled to meet with Polish President Andrzej Duda, a key ally of Kyiv and an outspoken critic of Moscow’s ongoing “special military operation.”

On Monday, Biden’s visit to Kyiv came as a surprise to the world. He met with Ukrainian President Volodymyr Zelenskyy and walked along a street near the renowned St. Michael’s Golden-Domed Monastery. The White House informed Russia of Biden’s visit to Kyiv hours before his departure for “deconfliction purposes,” according to White House National Security Adviser Jake Sullivan. Only a few of Biden’s closest aides accompanied him on the trip, including Sullivan. Sullivan said that it was “a historic visit unprecedented in modern times to have the president of the United States visit the capital of the country at war where the United States military does not control the critical infrastructure.”

During his trip in Warsaw, Biden is expected to deliver a speech commemorating the one-year anniversary of Russia’s invasion of Ukraine. Biden previously visited Poland last year after the initial invasion. During that visit, he denounced Russian President Vladimir Putin, though the White House later walked back the statement. In December, Biden hosted President Zelenskyy in Washington and reaffirmed the U.S.’s “unwavering” support for Ukraine’s war effort. Since Biden took office in January 2021, the United States has provided Ukraine with around $25 billion in security assistance.

Poland has also been a major supporter of Kyiv since the conflict began. It has already provided Ukraine with 250 combat tanks and has pledged dozens more, including advanced German-made Leopard tanks. Biden’s visit to Warsaw is meant to bring together Kyiv’s allies in the face of waning support for the war in Europe and the United States. Republican lawmakers, who won control of the House of Representatives last year, have expressed increasing opposition to continued assistance.

While in Poland, Biden is also expected to meet with leaders of the Bucharest Nine (B9), a group of East European NATO allies established in 2015. The B9 consists of Bulgaria, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Romania, and Slovakia. All B9 members were part of the former Soviet Union or the Soviet-led Warsaw Pact.

Over the last year, Russian forces have captured large parts of the eastern, Russian-speaking Donbass region and along the country’s southern Black Sea coast. After holding referendums last October, Moscow announced the unilateral annexation of the Donetsk, Luhansk, Zaporizhzhia, and Kherson regions. Kyiv and its Western allies reject the legitimacy of the move. Ukrainian military officials have vowed to recover all lost territory by force of arms.

In the lead-up to Biden’s Poland visit, speculation has grown that the conflict’s upcoming anniversary could coincide with fresh Russian offensives along several parts of the 600-mile-long frontline.