TOKYO (AP) — Japan on Wednesday criticized Russia’s announcement that it is suspending an agreement allowing Japanese to fish in waters near disputed islands, as relations between the countries deteriorate over the war in Ukraine.

The fishing deal has been in place since 1998 and allows Japanese fishing boats to operate around the Russian-held Kurils, which Japan also claims and calls the Northern Territories, in exchange for payments from Japan based on catch quotas and other conditions negotiated annually.

Its suspension, apparently in response to Japan’s sanctions against Moscow for its invasion of Ukraine, raises concern about the safety of Japanese fishing boats in the area. Prior to the agreement, Russian authorities had seized and sometimes shot at Japanese boats.

Chief Cabinet Secretary Hirokazu Matsuno said it was “regrettable that Russia one-sidedly announced it is suspending the cooperation in this manner.” He criticized Moscow for blaming Japan’s failure to fund unrelated development projects on Sakhalin, Russia’s largest island in the Pacific and not part of the territory claimed by Tokyo.

Japan has provided development funds for Sakhalin for years as part of its efforts to improve ties with Russia. Matsuno acknowledged that Tokyo had not made its latest payment for the Sakhalin projects, but it wasn’t immediately clear if it was related to the sanctions.

Matsuno said Tokyo will pursue negotiations to ensure safe operations of Japanese boats under the pact.

“We will do our utmost to protect the safety of the Japanese fishing operation,” he said.

The area is a rich fishing ground for pollack, Okhotsk mackerel and octopus.

The fishing safety pact is one of four fisheries agreements near the disputed waters. Negotiations on two others — one involving Russian salmon and another seaweed — were settled earlier this year, while a fourth deal to decide catch quotas in each other’s economic waters is set for December.

The territorial dispute has prevented the two countries from signing a peace treaty formally ending their World War II hostilities. Russia has already scrapped peace treaty negotiations with Japan in response to the sanctions.

Also Wednesday, Japan’s Defense Ministry said four suspected Russian fighter jets flew over the Sea of Japan toward Japanese airspace west of the island of Hokkaido on Tuesday night, causing Japan’s Air Self-Defense Force to scramble its fighter jets.

They did not violate Japanese airspace, the ministry said in a statement.

Japan quickly joined the United States and Europe in imposing sanctions against Russia and providing support for Ukraine after Russia’s invasion. It fears the crisis may embolden China to increase its assertiveness in the region.

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