Tokyo: Japan said on Wednesday that Tokyo would "strongly protest" to Russia over military exercises on disputed Pacific islands that have strained relations between the two nations since the end of World War Two.
The exercises on the islands are a blow to Prime Minister Shinzo Abe`s efforts to court resource-rich Russia and keep the door open to dialogue with Moscow, despite the Ukraine crisis.
The dispute over the islands, which Russia seized from Japan in the waning days of World War Two, has also prevented the two countries from signing a formal peace treaty.
The islands are known as the Southern Kuriles in Russia and the Northern Territories in Japan.
"Given our nation`s legal stance regarding the Northern Territories, the fact of the Russian military exercises there is totally unacceptable," a Foreign Ministry official said.
"We have already expressed these thoughts to Russia, but with the start of these recent exercises, we will once again strongly protest."
Colonel Alexander Gordeyev, a spokesman for Russia`s Eastern Military District, told the Russian news agency Interfax on Tuesday that exercises had begun, involving military units in the region, which were deploying to the islands.
Gordeyev said more than 1,000 troops, five Mi-8AMTSh attack helicopters and 100 other pieces of military hardware would be involved in the manoeuvres.
The exercises included Etorofu and Kunashiri islands, which Tokyo claims. It also claims Shikotan island and the Habomai islet group.
Russia is at odds with Western powers over what NATO says is its massing of military forces along the border with Ukraine for a possible invasion to boost pro-Russian separatists in the country`s east. Moscow denies any such intent.
Abe, however, has made an effort to improve Japan`s ties with resource-rich Russia a key aspect of his diplomacy.
His government treads a fine line by imposing sanctions on Moscow in step with ally the United States, but keeps them lighter than those ordered by Washington in a bid to keep relations with Russia from going into a deep chill.