"They [Japan] support the sanctions regime, and this is one of the issues, one of the situations, which seriously hamper the signing of the peace treaty," Peskov told the Rossiya 1 broadcaster.
At the Eastern Economic Forum (EEF) in September, Putin proposed Japan to sign the peace treaty without any preconditions by the end of 2018, but it had found no understanding on the part of Tokyo, Peskov noted.
The Russian-Japanese relations have long been complicated by the fact that the two nations never signed a permanent peace treaty after the end of World War II. The deal was never reached because of a disagreement over a group of four islands — Iturup, Kunashir, Shikotan and Habomai — that are claimed by both countries. They are collectively referred to as the Southern Kurils by Russia and the Northern Territories by Japan.