Photo/Illutration A memorial service is held at sea in July 2022 by former residents of the Northern Territories. (Provided by league of former residents of Chishima and Habomai islands)

Russian authorities have effectively banned an organization of former residents of the disputed Northern Territories campaigning for Japanese sovereignty, further complicating efforts to improve bilateral relations.

Russia’s prosecutor general on April 21 announced that it had designated the league of residents of Chishima and Habomai islands as “an undesirable organization.”

It was the first time any Japanese organization had received that designation, the Interfax news agency reported.

The move was seen as further retaliation against Japan for siding with Western nations in imposing economic sanctions against Russia for its invasion of Ukraine.

Moscow last September unilaterally revoked a bilateral agreement on visa-free visits to the Northern Territories by former residents. Even if that measure is reinstated, members of the residents’ league will likely no longer be allowed to visit the four islands that Soviet forces seized in the waning days of World War II.

Russian authorities said the league had sought to upend Russia’s constitutional order and national security framework. Any actions by the group in Russia, including the Northern Territories now effectively controlled by Moscow, will be considered illegal.

They said the league was threatening to violate Russia’s territorial integrity with its campaign to return sovereignty of the Northern Territories to Japan.

The group was accused of devoting many years to “heightening anti-Russian sentiment in Japan by forming negative views about Russia as well as increasing the risk of destabilizing the area around the Kuril Islands (the Russian name for the area covering the Northern Territories and Chishima islands).”