Russia and Japan have still not signed a peace treaty to end World War II.

Nearly 70 years on, two countries that never fought each other on the level that the Soviet Union did with Germany, or the level that Japan did with the United States continue to have a dispute over four islands. Though today, Germany and Russia as well as Japan and the US have fairly good relationships, the four Southern Kurile islands remain an issue of conflict between Japan and Russia. 

As World War II drew to a close, Soviet forces had occupied these islands, but today both countries consider these islands to be theirs. In September 1951, the Soviet Union declined to sign the San Francisco Peace Treaty because Japan believed the four islands were theirs. It has been a source of conflict ever since. Japan still considers the islands theirs, and Russia still considers them theirs. 

There have been countless attempts to remedy the problem over the years, but none have proved successful. Perhaps, like the German Chancellor, Japanese Prime Minister Yoshihiko Noda also has a fear of dogs that Vladimir Putin can use to put an end to the issue. 

(Source)