Japan's Prime Minister Shinzo Abe and US President Barack Obama have agreed on the importance of maintaining Ukraine's sovereignty and territorial integrity.

Abe spoke with Obama over the phone on Friday.

The United States has imposed sanctions on Russia, which has effectively taken control of Ukraine's Autonomous Republic of Crimea. The measures include visa restrictions for high-ranking Russian officials.

Abe said the Japanese government supports the Obama administration's efforts to improve the situation in Ukraine. He added that Japan also hopes to see early improvements.

The White House said Obama and Abe share the view that Russia's actions pose a threat to global peace and security.

It said the leaders confirmed that Japan and the US will cooperate with their Group of 7 partners to ensure that Russia will respect Ukraine's sovereignty on the basis of the UN Charter.

The White House said the 2 leaders also agreed to help the Ukrainian interim government to achieve economic stability and to hold a successful presidential election in May.