Japanese Prime Minister Shinzo Abe has said talks are needed with Russian President Vladimir Putin for the countries to forge a peace treaty.
Japan and Russia never signed a peace treaty after World War II because of territorial disputes over islands north of the Japanese island of Hokkaido, which Japan calls its "Northern Territories."
Abe also told a news conference in Tokyo on January 4 that it was crucial that Russia play a constructive role in fighting terrorism and in the crises in Iran and Syria.
Since taking office in late 2012, Abe has sought to make progress on improved relations with Russia, but the conflict in Ukraine and other issues have complicated that effort.
Several tentative plans for a visit by Putin to Japan have been put off due to Western concerns over Russia's involvement in such crises.