The most difficult item on Japan's international agenda in the coming year will be ties with Moscow. This view by Japanese Foreign Minister Shintaro Abe reflects the clearly adversarial between Tokyo and Moscow. But Abe said last week that he thought ''there are some signs of burgeoning'' in the bilateral relationship. He cited Prime Minister Yasuhiro Nakasone's encounter with Prime Minister Nikolai Tikhonov last week at Indira Gandhi's funeral - the first meeting between Japanese and Soviet chiefs of government in 11 years.
Tokyo claims the so-called four northern islands off the eastern coast of Hokkaido that Moscow has been occupying since World War II. This claim must be settled, Tokyo insists, before a peace treaty can be signed.
Although the Soviets have refused to budge on the territorial issue, Japanese sources have noted that Mr. Tikhonov, in talks with Mr. Nakasone, did not repeat the stock Soviet phrase that there were no territorial issues left over from World War II between Moscow and Tokyo.
Japan will try to get Soviet Foreign Minister Andrei Gromyko to visit Japan next year, Abe said.
Moscow is known to be eager to obtain Japanese economic cooperation in Siberia development. Tokyo has no real hope of getting movement on the territorial issue in exchange for such cooperation. But Nakasone and Abe share the conviction that somehow or another, peace-threatening tensions in the Western Pacific must be reduced, and they see no way other than by patient, continuous dialogue with the Soviet Union.
(On Monday, however, a Soviet Tupolev-16 bomber violated Japan's air space despite warnings, Reuters reports. It flew over the eastern Tsushima Strait between Japan and South Korea. The Defense Ministry said it was the first violation of Japanese air space in a year.)
In his first trip to Washington as prime minister two years ago, Nakasone had described Japan as an ''unsinkable aircraft carrier.'' He told a recent Soviet visitor that his country was an ''unsinkable archipelago of peace and prosperity.''
Nakasone is said to be contemplating a trip to Washington in January. The purpose will be partly to head off looming trade tensions before they reach typhoon proportions. But even more important will be the solidifying of the Japanese-US partnership in world affairs, of which Tokyo's approach to Moscow is one symbol.