World War II ended in 1945, and in the decades since, Japan and Russia have never signed a peace treaty to formally end hostilities. That's partially because the two countries have been in a territorial dispute over islands—known as the Southern Kuriles or Kuril Islands in Russia and the Northern Territories in Japan—captured by Soviet troops in the final days of the war. Japan wants to strike a peace deal with Russia now, but in order to do that, Russia says Japan must recognize Russian sovereignty over the islands, Reuters reports. "These are not pre-conditions, it’s just an effort to understand why Japan is the only country in the world which cannot say: 'I accept the results of World War II in their entirety,'" Russian Foreign Minister Sergei Lavrov told reporters Wednesday, insisting that the move is not an ultimatum.
Japanese Foreign Minister Taro Kono was in Moscow holding talks about the dispute with Lavrov this week, and Japanese Prime Minister Shinzo Abe is scheduled to meet with Russian President Vladimir Putin Jan. 22. Both countries have seen protests over the issue of the islands, DW reports, with Japanese protesters calling for Japan to reclaim the islands and Russian protesters insisting their country not cede control of them. Newsweek notes that in 1956, the Soviet Union issued a joint declaration with Japan stating it was willing to give up control of two of the islands, and Russia is now asking Japan to accept that document as the basis for future discussions. (The Korean War has yet to formally end.)