TOKYO (REUTERS, AFP) - Russian President Vladimir Putin and Japanese Prime Minister Shinzo Abe kick off a summit on Thursday (Dec 15) aimed at reaching a deal over four islands that have prevented their countries from formally ending their World War II hostilities.
Despite months of preparation for the summit, the outlook is not good, with both sides recently damping down expectations of major progress.
Here are some key facts about the islands and the dispute:
What and where are the islands?
The four islands are collectively known as the Southern Kurils in Russia and the Northern Territories in Japan. They consist of Iturup (Etorofu in Japanese), Kunashir (Kunashiri), Shikotan and Habomailie. At their closest point, they lie just a few kilometres off the north coast of Hokkaido. On a clear day, Kunashiri is visible from Hokkaido.
They are the southernmost territories in a volcanic chain that separates the Sea of Okhotsk and the Pacific Ocean. They are located to the south-east of the Russian island of Sakhalin and are administratively part of the same region, although Tokyo considers them part of Hokkaido prefecture and "illegally occupied by Russia".
The islands' total land area is almost 5,000 sq km, according to Japan's foreign ministry.
Who live there?
The islands were home to about 17,000 Japanese people, who fished, bred horses and mined gold, among other occupations, before they were seized by the Soviet Union after it declared war on Japan in the closing days of World War II. The inhabitants were forced to flee.
The current population is 12,346, according to the Russian government. Most inhabitants depend on fishing for their livelihood and Japan would gain rich fishing grounds if it regains full control of the islands, partly through extending its exclusive economic zone.
Why are the islands important?
The islands are "important from all points of view", said Dr Valery Kistanov who heads the Centre for Japanese Studies at the Russian Institute of the Far East. "They are rich in hot springs and minerals and rare metals such as rhenium" which is used in production of supersonic aircraft, he said.
But the "greatest value" of the islands lies in their geographical location at the meeting of warm and cool water currents, which is beneficial both for fisheries and the Russian navy too, he said.
Strategically, control of the islands ensures Russia has year-round access to the Pacific Ocean for its Pacific Fleet of warships and submarines based in Vladivostok since the strait between Kunashir and Iturup does not freeze over in winter.
"This is why the Russian military is against any territorial concession, especially of Iturup and Kunashir," said expert James Brown who teaches at Temple University in Japan.
What's the history behind the islands?
Russian Empress Catherine the Great in 1786 claimed sovereignty over the Kuril islands after her government declared they were discovered by "Russian explorers" and therefore "undoubtedly must belong to Russia".
In the first treaty between tsarist Russia and Japan in 1855, the frontier between the two countries was drawn just north of the four islands closest to Japan. Twenty years later in 1875, a new treaty handed Tokyo the entire chain, in exchange for Russia gaining full control of the island of Sakhalin. Japan also seized back control of the southern half of Sakhalin after its crushing defeat of Moscow in the 1905 Russo-Japanese War.
The Kuril islands have been back at the centre of a dispute between Moscow and Tokyo since Soviet troops invaded them in the final days of World War II. The USSR only entered into war with Japan on Aug 9, 1945 just after the United States had dropped the atomic bomb on Hiroshima. The troops completed the takeover of the islands after Japan's general surrender later that month.
Russia argues that US President Franklin Roosevelt promised Stalin he could take back the Kurils in exchange for joining the war against Japan at the Yalta conference in February 1945 at which the Allied leaders divided up the post-war world.
The Soviet capture of the islands has since prevented Moscow and Tokyo from signing a formal peace treaty to end the war, despite repeated attempts over the past 70 years to reach a deal.
In 1956, Soviet leader Nikita Krushchev first offered to give Japan the two smallest islands, Shikotan and Habomai, in exchange for signing a peace treaty, but in the face of US opposition, those talks went nowhere.