Japan has lodged a protest with Russia for naming three uninhabited islets in the disputed Northern Territories mainly after Soviet-era politicians and military commanders.

“It is a highly regrettable decision because it does not concur with our nation’s position,” Chief Cabinet Secretary Yoshihide Suga told a news conference on Feb. 14.

The Russian government in 2010 started to name uninhabited isles in the Kurile island chain northeast of Hokkaido between the Sea of Okhotsk and the Pacific Ocean, but progress has been slow.

The southern part of the chain forms Japan’s Northern Territories--the Habomai islets and the islands of Shikotan, Kunashiri and Etorofu--which were seized by Soviet forces at the end of World War II. Japan has since been demanding that Moscow return the islands.

The Russian government apparently gave names to five small islets to underscore Moscow’s effective control over the territories.

Through diplomatic channels, Japan’s Foreign Ministry lodged a protest with Moscow on Feb. 13, saying, “It is regrettable for Russia to give names to Japanese land.”

In response, Dmitry Peskov, the press secretary of Russian President Vladimir Putin, said the following day, “The Kurile Islands are Russian territory and thus naming them is our sovereign right,” according to a report from the RIA Novosti news agency.

Moscow named one of the Habomai islets after Lt. Gen. Kuzma Derevyanko (1903-1954), who represented the Soviet Union in the Allied Council for Japan. The council was established shortly after World War II to handle Japan’s postwar process.

An islet near Urup Island was named after Andrei Gromyko (1909-1989), the Soviet foreign minister from 1957 to 1985.

The territorial dispute is the main reason why Tokyo and Moscow have not signed a formal peace treaty to end World War II.

“We hope to continue negotiating with Russia persistently with the fundamental aim of resolving the issue of jurisdiction over the four islands of the Northern Territories and signing a peace treaty,” Suga said.

(Akiyoshi Komaki in Moscow and Hitoki Nakagawa in Vladivostok contributed to this article.)