"Japan is closely following Russia's actions on the Northern Territories and is gathering information. On 12 March, a representation was made through diplomatic channels in connection with the Russian military's exercises on the islands. This leads to an increased military presence of Russian troops on the islands, is incompatible with the position of our country and is unacceptable", the Japanese ministry said.
Tokyo considers the territorial possession of the islands in a disputed chain off Japan’s northern tip to be an important issue and will continue to discuss it with Russia, the ministry added.
This comes after on Tuesday, Russian motorised rifle units began exercises in the south of the Kuril archipelago. About 500 troops and up to 70 pieces of military hardware, including tanks, participated in the manoeuvres. Japan issued a diplomatic note to Russia regarding the exercises.
Since Russian President Vladimir Putin's visit to Japan in December 2016, the relationship between the two nations has been improving, with the two sides agreeing to develop joint projects on the disputed territories.
During peace treaty talks with his Japanese counterpart in January, Russian Foreign Minister Sergei Lavrov stressed that the sides had confirmed their willingness to work on the basis of the 1956 declaration, "which means, first of all, the inalterability of… Japan’s complete recognition of… Russia’s sovereignty over all the islands of the South Kuril ridge".