Japan on Wednesday "regretted" that Russia suspended an agreement on fishing near the disputed Kuril Islands, calling it a "unilateral" decision.
"We regret that Russia unilaterally announced the suspension of the agreement," Hirokazu Matsuno, Japan's top government spokesperson told a news conference in Tokyo.
Moscow on Tuesday announced the suspension of the 1998 agreement with Japan on fishing near the Kuril Islands.
It said the step was taken because Tokyo violated its obligations under the agreement -- started delaying payments and stopped providing technical support to Russia's far eastern Sakhalin region, in return for which Moscow annually allocated a fishing quota for Japan.
Matsuno said Tokyo has lodged a protest with Moscow over the move.
Accepting that Tokyo "has not made the latest payment" for the project in Russia's far east region, Matsuno stressed that "the project is not a condition for continuing the agreement."
Moscow's suspension of the agreement also comes after Japan joined its western allies to sanction Russia due to the war it launched on Ukraine on Feb. 24.
Besides President Vladimir Putin and his aides, Tokyo has sanctioned many Russian entities and restricted investments in Russia.
Russia and Japan have not signed a peace treaty after World War II and have a territorial dispute over what Moscow calls the Southern Kuril Islands-a set of four islets controlled by Russia, which Japan identifies as the Northern Territories.
The 1998 safe fishing agreement was "concluded following a series of captures and shootings on fishing vessels by Russian authorities," Kyodo News reported.
Russia, under the agreement, allows Japan to fish around the disputed islands in exchange for paying "cooperation money."
At the 1945 Yalta Conference, the Soviet Union agreed to start military operations on the eastern front under an agreement with its western allies, and in exchange, received some Japanese territories, including the Kuril Islands.
After the war, however, with the start of the Cold War, supported by Western countries, Japan rejected the Soviet Union's sovereignty over the islands.
Due to the dispute, Russia and Japan have never signed a peace treaty and are technically still at war. As both sides claim the territories, the question of the Kurils' sovereignty remains uncertain.
Tokyo regularly protests visits of Russian officials to the islands.
Russian authorities fear the possible deployment of US missile systems on the islands if they are returned to Japan, creating a direct military threat to Russia.
