President Barack Obama and Prime Minister Shinzo Abe of Japan spoke Thursday and agreed that Russia's actions in Ukraine threaten world peace and security, the White House said.
The statement said the two leaders "emphasized the importance of preserving Ukraine's sovereignty and territorial integrity."
It said the Obama and Abe also pledged to work through the International Monetary Fund to support Ukraine's government.
Obama is set to visit Japan in April on a trip that will also take him to South Korea, Malaysia and the Philippines. He was forced to skip a trip to Malaysia and the Philippines last fall because of the government shutdown.
Abe visited Sochi last month for the opening of the Winter Olympics and met with Russian President Vladimir Putin then.