The United States urged Japan and Russia to resolve a dispute over four islands that have been a sore point in relations between the two countries for decades, dpa reported.
The issue arose on Monday after Russian President Dmitry Medvedev visited one of the South Kiril islands, becoming the first leader of the country - including the Soviet era - to do so. Japan claims the islands and refers to them as the Northern Territories.
"We do back Japan regarding the Northern Territories," State Department spokesman PJ Crowley said. "But this is why the United States, for a number of years, has encouraged Japan and Russia to negotiate an actual peace treaty regarding these and other issues."
The Soviets occupied the islands at the conclusion of World War II and Russia has continued to exercise authority over them. Japanese Prime Minister Naoto Kan called Medvedev's visit "regrettable."
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