These, with a number of smaller conflicts, prevented both countries from signing a peace treaty after World War II, and even today matters remain unresolved.

Strains in Japan–Soviet Union relations have deep historical roots, going back to the competition of the Japanese and Russian empires for dominance in Northeast Asia.

The Imperial Japanese Army also penetrated as far west as Lake Baikal and Buryatia, occupying the city of Chita in Transbaikal until October 1920.

An important step during this period was the conclusion on January 23, 1928, of a Soviet-Japanese Fishery agreement, which permitted Japanese nationals to fish in the waters of the Pacific Ocean adjacent to the Soviet coastline.

[5] After the Japanese invasion of Manchuria and the establishment of the puppet state of Manchukuo in 1932, Japan turned its military interests to Soviet territories.

At Yalta in February 1945, Stalin promised Roosevelt that the USSR would enter the war against Japan 90 days after the defeat of Germany, which took place in May.

[8] Due to the invasion, 56 islands of the Kuril chain, as well as the southern half of Sakhalin (i.e. the Northern Territories), were in 1946 incorporated into the Soviet Union.

This annexation was never recognized by Japan and prevented the conclusion of a Soviet-Japanese World War II peace treaty and the establishment of closer relations between the two states.

Negotiations resumed, however, and the Soviet Union and Japan signed a Joint Declaration on October 19, 1956, providing for the restoration of diplomatic relations and ending the war.

In addition, the Soviet Union pledged to support Japan for UN membership and waive all World War II reparations claims.

As early as 1956, it hinted at the possibility of considering the return of the Habomai Islands and Shikotan if Japan abandoned its alliance with the United States.

Despite divergence on the territorial question, on which neither side was prepared to give ground, Japan's relations with the Soviet Union improved appreciably after the mid-1960s.

Other high-level talks, including an October 1973 meeting between Prime Minister Tanaka Kakuei and Leonid I. Brezhnev, general secretary of the Communist Party of the Soviet Union, were held in Moscow during the next three years, but the deadlock on the territorial issue continued, and prospects for a settlement dimmed.

He also reportedly warned the Japanese, in a reference to China, against "forces which come out against the relaxation of tension and which try to complicate relations between states, including our countries."

Despite Japanese protestations that the treaty's antihegemony clause was not directed against any specific country, Moscow saw it as placing Tokyo with Washington and Beijing firmly in the anti-Soviet camp.

It responded by cutting off contacts beneficial to the Soviet regime and providing assistance to "front line" states, such as Pakistan and Thailand.

Under Prime Minister Yasuhiro Nakasone, Japan worked hard to demonstrate a close identity of views with the Reagan administration on the "Soviet threat".

This economic cooperation was interrupted by Japan's decision in 1980 to participate in sanctions against the Soviet Union for its invasion of Afghanistan and by its actions to hold in abeyance a number of projects being negotiated, to ban the export of some high-technology items, and to suspend Siberian development loans.

The advent of the Mikhail Gorbachev regime in Moscow in 1985 saw a replacement of hard-line Soviet government diplomats who were expert in Asian affairs with more flexible spokespersons calling for greater contact with Japan.

By 1990, Japan appeared to be the least enthusiastic of the major Western-aligned developed countries in encouraging greater contacts with and assistance to the Soviet Union.

Changes in Soviet policy carried out under Gorbachev beginning in the mid-1980s, including attempts at domestic reform and the pursuit of détente with the United States and Western Europe, elicited generally positive Japanese interest, but the Japanese government held that the Soviet Union had not changed its policies on issues vital to Japan.

During the visit, although various substantive issues, including the Northern Territories and the signing of a peace treaty, were discussed, no significant improvement was seen in Japan-Russia relations.

Complicating economic relations between Japan and the Soviet Union were the Cold War realities and the above-mentioned territorial disputes.

The challenges to détente, especially the invasion of Afghanistan in 1979, and falling raw material prices put strong constraints on Japan's trade and investment relations with the Soviet Union.

Only after Soviet policy began to change under Mikhail Gorbachev's leadership, beginning in 1985, did Japanese trade resume its growth.