A leftist Russian MP Oleg Mikheyev has proposed the Foreign Ministry freeze all territorial talks with Japan until it recognizes the results of Crimea’s referendum on joining Russia.

“If Japan is throwing a spanner in the works of our diplomacy in Ukraine and at the same time hopes to continue with a diplomatic settlement of the Kuril Islands issue, this is their harsh mistake,” the politician emphasized in his letter.

Earlier, Japan’s Foreign Minister Fumio Kishida expressed regret over Crimea’s secession from Ukraine and called upon Russian leaders to withdraw acceptance of the republic’s sovereignty. He also announced that Japan was introducing sanctions against Russia.

Russia and Japan are in dispute over four of the southernmost islands in the Kuril Archipelago that fell under Soviet control after WW2.

The territorial dispute prevented the two countries from signing a peace treaty and relations are still regulated under the armistice.