Ukraine's President Volodymyr Zelensky met U.S. Secretary of State Antony Blinken during the latter's visit to Kyiv on May 14.

The president thanked Blinken for the "crucial package" of $61 billion in U.S. aid passed by Congress in April. While this decision unblocked the flow of American assistance after six months of delays, it will likely still take some time before the effects are felt on the battlefield.

"A big appreciation from Ukrainians to Americans for this," Zelensky said.

U.S. Secretary of State Antony Blinken visited Ukraine on Tuesday on an unannounced diplomatic mission to reassure the country amid its war with Russia.

After arriving in Kyiv, Blinken is expected to meet with senior Ukrainian officials and "highlight the United States’ enduring support for Ukraine," the U.S. State Department said. In the Ukrainian capital, he will also underscore the Biden administration’s commitment to Ukraine’s defense and assure Ukraine that it has America’s support against increasingly intense Russian attacks.

US Secretary of State Antony Blinken made a surprise trip to Kyiv on Tuesday, meeting with President Volodymyr Zelensky as Russian forces make significant gains on the battlefield in Ukraine.

Blinken’s visit was the first by a Biden administration official since the long-delayed passage of US supplemental funding to the war-torn country.

The top US diplomat is due to deliver a speech later Tuesday, and discussed “recent battlefield updates in his meeting with Zelensky.