"It's an important step on the path to victory," Zelenskyy, he turned 45 on Wednesday, tweeted, thanking Biden for his "powerful" decision.

The United States announced earlier Wednesday that it will provide 31 Abrams tanks to help Ukraine repel Russia's invasion, mirroring a similar move by Germany in the face of dire warnings from Moscow.

The twin announcements will come as a major relief for Kyiv which has pleaded for months for heavy Western tanks to aid its battle.

"A historic day," Andriy Yermak, the head of Ukraine's presidential administration, said on messaging app Telegram. "One of those days that will determine our future victory," he added.

He also thanked Biden, Congress and the American people.

"We'll never forget it," he added. "The great time is coming."