Japan announced on Monday that it had protested Russian plans to hold military exercises off the disputed Kuril Islands, as reported by Japanese local media.
Moscow announced that the military exercise was set to start the next day in the sea off of Kunashiri, the southernmost of the islands.
Japanese chief cabinet secretary Hirokazu Matsuno said Tokyo has lodged a protest on Thursday after Moscow issued an alert, saying it would hold intermittent target practice until March 1 in the sea southeast of Kunashiri, as reported by Kyodo news agency.
The dispute over the territories is one of the main reasons Japan and Russia never signed a peace treaty and, technically, are still at war ever since Russia declared war on Japan during the World War II.
Statements have been made by Russian politicians, including by Foreign Minister Sergey Viktorovich Lavrov claiming Russian ownership of the islands, and that the Russian government has no intentions of ever giving them back to Japan and refuses to discuss the matter.
The Kuril Islands is a volcanic archipelago, located 1,300 km northeast of Hokkaido in Japan in the sea of Okhotsk. It contains 56 islands and cover about 10.5 sq. km. The islands have been under Russian control since 1945, but Japan claims the four southernmost ones.