TOKYO, June 24. /TASS/. Japan’s government has expressed protest to Russia over military drills involving Eastern Military District units and the Pacific Fleet forces in the southern part of the Kuril Islands, Japanese Chief Cabinet Secretary Katsunobu Kato told a press conference on Thursday.

"We are watching the activities of the Russian military on the northern territories (the term used in Japan to refer to the South Kuril Islands - TASS). On June 23, we expressed protest via diplomatic channels over the fact that Russia’s bigger military presence on these islands, including such drills, run counter to our position," he said.

The press service of Russia’s Eastern Military District said on Wednesday that five-day military drills involving 10,000 troops, 500 vehicles and 12 warships and vessels had kicked off on the islands of Sakhalin, Iturup, and Kunashir.

Russia and Japan have been negotiating a peace treaty after World War II since the mid-20th century. The main stumbling block to this is the issue of the ownership of the southern Kuril Islands. After the end of World War II, all Kuril Islands were incorporated into the Soviet Union. However, Japan challenged the ownership of Iturup, Kunashir, Shikotan islands and a number of uninhibited islands of the Lesser Kuril Ridge called the Habomai Islands in Japan.

In 1956, the Soviet Union and Japan signed a joint declaration on ceasing the state of war. The two countries resumed diplomatic and other relations, however no peace treaty has been signed until now.

The Russian foreign ministry has repeatedly said that Russia’s sovereignty over these islands, which is committed to paper in international documents, cannot be called to question.