By Roland Buerk
BBC News, Tokyo
The talks came at the opening of a major LNG plant in Sakhalin
Japanese Prime Minister Taro Aso and Russian President Dmitry Medvedev have held talks on resolving a decades-old territorial dispute.
The two men met at the inauguration of a Russian liquefied natural gas plant of which Japan will be a key customer.
The visit of Mr Aso to Sakhalin Island in Russia's Far East is seen as symbolic in Japan.
He is the first Japanese PM to set foot on the island, parts of which were once in Japanese hands, since World War II.
Japan and Russia have never signed a formal peace treaty because they have been in dispute over four other islands occupied by Soviet forces.
What Russia calls the Southern Kurils are known in Japan as the Northern Territories.
They are south-east of Sakhalin, off the northern Japanese island of Hokkaido.
After the talks Mr Aso said he and Mr Medvedev had agreed to accelerate their efforts to resolve the territorial dispute without leaving it to future generations.
The meeting was held as both men attended the opening of a Russian liquefied natural gas plant.
Russia's state-run Gazprom took control of the Sakhalin-2 project in 2006 from Royal Dutch Shell after regulators threatened to close it down on environmental grounds.
Japan will be a major customer, keen to diversify its energy supply beyond the Middle East.
Russia aims to boost exports to Asia.