President Joe Biden on Monday made an unannounced visit to Kyiv and met with Ukrainian President Volodymyr Zelenskyy, ahead of the one-year anniversary of Russia’s war against Ukraine later this week.

Biden was previously scheduled to depart the U.S. for Warsaw, Poland, later Monday.

This marks Biden’s first visit to the country since Russia’s invasion on Feb. 24, 2022.

“When [Russian President Vladimir] Putin launched his invasion nearly one year ago, he thought Ukraine was weak and the West was divided,” Biden said in a statement. “He thought he could outlast us. But he was dead wrong.”

Biden pledged to announce an additional delivery of equipment later this week, as well as apply new sanctions “against elites and companies that are trying to evade or backfill Russia’s war machine.”

Zelenskyy shared a photo on his Telegram account, showing him and Biden sharing a handshake.

“Your visit is an extremely important sign of support for all Ukrainians,” Zelenskyy wrote.

Biden is due to meet with Polish President Andrzej Duda on Tuesday, and also deliver remarks reiterating U.S. support to Ukraine “for as long as it takes.”

This is a developing story. Please check back for updates.