A spokesman for Russian President Vladimir Putin said Monday he sees progress in sight for his country’s decades-old territorial dispute with Japan, and that stronger bilateral economic ties are key to it, Russia’s Interfax news agency reported.

“A breakthrough is possible in theory…a certain consensus will be achieved sooner or later,” Kremlin spokesman Dmitry Peskov was quoted as saying in Turkey, where Putin has been attending a global energy summit.

His remarks came ahead of Putin’s visit to Japan in December, during which the row over Russian-held, Japanese-claimed islands off Japan’s northernmost main island of Hokkaido will figure high in the leader’s summit with Japanese Prime Minister Shinzo Abe.

According to Interfax, Peskov said that settling the territorial dispute “requires more patience” and “a gradual approach” based on mutual trust forged by boosting economic and trade relations.

Demonstrating Russia’s keen interest in Japan’s economic cooperation, Peskov welcomed Abe’s policy of boosting economic ties with Russia as a “very constructive approach.”

Putin’s administration has shown a strong interest in an eight-point Japanese economic cooperation plan Abe presented to the Russian leader in Sochi in May, in the hope of boosting economic ties and advancing talks on the islands.

“We are going in the right direction, and there is a reason for optimism,” Peskov said, but did not elaborate on what he meant by a consensus on the isles row.

The dispute over the islands, called the Northern Territories in Japan and the Southern Kurils in Russia, has prevented Tokyo and Moscow from concluding a postwar peace treaty.

Russia continues to stand by the 1956 Japan-Soviet Joint Declaration, which says Russia will hand over two of the four islands, the smaller Shikotan and the Habomai group, after concluding a peace treaty with Japan.