A decadeslong territorial row may be taking a new turn as Japan and Russia look set to uphold a 1956 joint declaration in which Moscow promised to hand over two disputed islands to Tokyo once a peace treaty was signed.

Prime Minister Shinzo Abe agreed with Russian President Vladimir Putin during a summit Wednesday in Singapore that they will accelerate peace treaty talks based on the document, in which Moscow vowed to return Shikotan and the Habomai islet group.

The dispute over the islands off Hokkaido, seized by the Soviet Union following Japan's surrender in World War II in 1945, has long been a thorn in bilateral relations, preventing them from concluding a postwar peace treaty.