Disputes about the four South Kuril Islands, which currently belong to the Russian Federation, have been going on for quite some time. As a result of agreements and wars signed at different times, this land changed hands several times. Currently, these islands are the cause of an unresolved territorial dispute between Russia and Japan.
Discovery of the islands
The issue of the discovery of the Kuril Islands is controversial. According to the Japanese side, the Japanese were the first to set foot on the islands in 1644. A map of that time with the designations marked on it - “Kunashiri”, “Etorofu”, etc. is carefully preserved in the National Museum of Japan. And Russian pioneers, the Japanese believe, first came to the Kuril ridge only during the time of Tsar Peter I, in 1711, and on the Russian map of 1721 these islands are called “Japanese Islands”.
But in reality the situation is different: firstly, the Japanese received the first information about the Kuril Islands (from the Ainu language - “kuru” means “a person who came from nowhere”) from the local Ainu residents (the oldest non-Japanese population of the Kuril Islands and the Japanese Islands) during an expedition to Hokkaido in 1635. Moreover, the Japanese did not reach the Kuril lands themselves due to constant conflicts with the local population.
It should be noted that the Ainu were hostile to the Japanese, and initially treated the Russians well, considering them their “brothers”, due to the similarity in appearance and methods of communication between the Russians and small nations.
Secondly, the Kuril Islands were discovered by the Dutch expedition of Maarten Gerritsen de Vries (Fries) in 1643, the Dutch were looking for the so-called. "Golden Lands" The Dutch did not like the lands, and they sold their detailed description and map to the Japanese. It was on the basis of Dutch data that the Japanese compiled their maps.
Thirdly, the Japanese at that time did not control not only the Kuril Islands, but even Hokkaido; only their stronghold was in its southern part. The Japanese began conquering the island at the beginning of the 17th century, and the fight against the Ainu continued for two centuries. That is, if the Russians were interested in expansion, then Hokkaido could become a Russian island. This was made easier by the good attitude of the Ainu towards the Russians and their hostility towards the Japanese. There are also records of this fact. The Japanese state of that time did not officially consider itself the sovereign of not only Sakhalin and the Kuril lands, but also Hokkaido (Matsumae) - this was confirmed in a circular by the head of the Japanese government, Matsudaira, during Russian-Japanese negotiations on the border and trade in 1772.
Fourthly, Russian explorers visited the islands before the Japanese. In the Russian state, the first mention of the Kuril lands dates back to 1646, when Nekhoroshko Ivanovich Kolobov gave a report to Tsar Alexei Mikhailovich about the campaigns of Ivan Yuryevich Moskvitin and spoke about the bearded Ainu inhabiting the Kuril Islands. In addition, Dutch, Scandinavian and German medieval chronicles and maps report about the first Russian settlements in the Kuril Islands at that time. The first reports about the Kuril lands and their inhabitants reached the Russians in the middle of the 17th century.
In 1697, during the expedition of Vladimir Atlasov to Kamchatka, new information about the islands appeared; the Russians explored the islands as far as Simushir (an island in the middle group of the Great Ridge of the Kuril Islands).
XVIII century
Peter I knew about the Kuril Islands; in 1719, the tsar sent a secret expedition to Kamchatka under the leadership of Ivan Mikhailovich Evreinov and Fyodor Fedorovich Luzhin. Marine surveyor Evreinov and surveyor-cartographer Luzhin had to determine whether there was a strait between Asia and America. The expedition reached the island of Simushir in the south and brought local residents and rulers to swear allegiance to the Russian state.
In 1738-1739, the navigator Martyn Petrovich Shpanberg (Danish by origin) walked along the entire Kuril ridge, put all the islands he encountered on the map, including the entire Small Kuril ridge (these are 6 large and a number of small islands that are separated from the Great Kuril ridge in the South -Kuril Strait). He explored the lands as far as Hokkaido (Matsumaya), bringing the local Ainu rulers to swear allegiance to the Russian state.
Subsequently, the Russians avoided voyages to the southern islands and developed the northern territories. Unfortunately, at this time, abuses against the Ainu were noted not only by the Japanese, but also by the Russians.
In 1771, the Lesser Kuril Ridge was removed from Russia and came under the protectorate of Japan. The Russian authorities sent the nobleman Antipin with the translator Shabalin to rectify the situation. They were able to persuade the Ainu to restore Russian citizenship. In 1778-1779, Russian envoys brought more than 1.5 thousand people from Iturup, Kunashir and even Hokkaido into citizenship. In 1779, Catherine II freed those who had accepted Russian citizenship from all taxes.
In 1787, the “Extensive Land Description of the Russian State...” contained a list of the Kuril Islands up to Hokkaido-Matsumaya, the status of which had not yet been determined. Although the Russians did not control the lands south of Urup Island, the Japanese were active there.
In 1799, by order of seii-taishogun Tokugawa Ienari, he headed the Tokugawa Shogunate, two outposts were built on Kunashir and Iturup, and permanent garrisons were placed there. Thus, the Japanese secured the status of these territories within Japan by military means.
Satellite image of the Lesser Kuril Ridge
Treaty
In 1845, the Empire of Japan unilaterally declared its power over all of Sakhalin and the Kuril ridge. This naturally caused a violent negative reaction from the Russian Emperor Nicholas I. But the Russian Empire did not have time to take action; the events of the Crimean War prevented it. Therefore, it was decided to make concessions and not bring matters to war.
On February 7, 1855, the first diplomatic agreement was concluded between Russia and Japan - Treaty of Shimoda. It was signed by Vice Admiral E.V. Putyatin and Toshiakira Kawaji. According to Article 9 of the treaty, “permanent peace and sincere friendship between Russia and Japan” were established. Japan ceded the islands from Iturup and to the south, Sakhalin was declared a joint, indivisible possession. Russians in Japan received consular jurisdiction, Russian ships received the right to enter the ports of Shimoda, Hakodate, and Nagasaki. The Russian Empire received most favored nation treatment in trade with Japan and received the right to open consulates in ports open to Russians. That is, in general, especially considering the difficult international situation of Russia, the agreement can be assessed positively. Since 1981, the Japanese have celebrated the day of signing the Shimoda Treaty as “Northern Territories Day.”
It should be noted that in fact, the Japanese received the right to the “Northern Territories” only for “permanent peace and sincere friendship between Japan and Russia,” most favored nation treatment in trade relations. Their further actions de facto annulled this agreement.
Initially, the provision of the Shimoda Treaty on joint ownership of Sakhalin Island was more beneficial for the Russian Empire, which was actively colonizing this territory. The Japanese Empire did not have a good navy, so at that time it did not have such an opportunity. But later the Japanese began to intensively populate the territory of Sakhalin, and the question of its ownership began to become increasingly controversial and acute. The contradictions between Russia and Japan were resolved by signing the St. Petersburg Treaty.
St. Petersburg Treaty. It was signed in the capital of the Russian Empire on April 25 (May 7), 1875. Under this agreement, the Empire of Japan transferred Sakhalin to Russia as full ownership, and in exchange received all the islands of the Kuril chain.
St. Petersburg Treaty of 1875 (Japanese Foreign Ministry Archive).
As a result of the Russo-Japanese War of 1904-1905 and Treaty of Portsmouth On August 23 (September 5), 1905, the Russian Empire, according to Article 9 of the agreement, ceded southern Sakhalin to Japan, south of 50 degrees north latitude. Article 12 contained an agreement to conclude a convention on Japanese fishing along the Russian shores of the Japanese, Okhotsk and Bering Seas.
After the death of the Russian Empire and the beginning of foreign intervention, the Japanese occupied Northern Sakhalin and participated in the occupation of the Far East. When the Bolshevik Party won the Civil War, Japan did not want to recognize the USSR for a long time. Only after the Soviet authorities canceled the status of the Japanese consulate in Vladivostok in 1924 and in the same year the USSR was recognized by Great Britain, France and China, the Japanese authorities decided to normalize relations with Moscow.
Beijing Treaty. On February 3, 1924, official negotiations between the USSR and Japan began in Beijing. Only on January 20, 1925, the Soviet-Japanese convention on the basic principles of relations between countries was signed. The Japanese pledged to withdraw their forces from the territory of Northern Sakhalin by May 15, 1925. The declaration of the USSR government, which was attached to the convention, emphasized that the Soviet government did not share with the former government of the Russian Empire political responsibility for the signing of the Portsmouth Peace Treaty of 1905. In addition, the convention enshrined the agreement of the parties that all agreements, treaties and conventions concluded between Russia and Japan before November 7, 1917, except for the Portsmouth Peace Treaty, should be revised.
In general, the USSR made great concessions: in particular, Japanese citizens, companies and associations were granted the rights to exploit natural raw materials throughout the Soviet Union. On July 22, 1925, a contract was signed to grant the Japanese Empire a coal concession, and on December 14, 1925, an oil concession in Northern Sakhalin. Moscow agreed to this agreement in order to stabilize the situation in the Russian Far East, since the Japanese supported the White Guards outside the USSR. But in the end, the Japanese began to systematically violate the convention and create conflict situations.
During the Soviet-Japanese negotiations that took place in the spring of 1941 regarding the conclusion of a neutrality treaty, the Soviet side raised the issue of liquidating Japan's concessions in Northern Sakhalin. The Japanese gave their written consent to this, but delayed the implementation of the agreement for 3 years. Only when the USSR began to gain the upper hand over the Third Reich did the Japanese government implement the agreement that had been given earlier. Thus, on March 30, 1944, a Protocol was signed in Moscow on the destruction of Japanese oil and coal concessions in Northern Sakhalin and the transfer of all Japanese concession property to the Soviet Union.
February 11, 1945 at the Yalta conference three great powers - the Soviet Union, the United States, Great Britain - reached a verbal agreement on the USSR's entry into the war with the Japanese Empire on the terms of the return of South Sakhalin and the Kuril ridge to it after the end of World War II.
In the Potsdam Declaration dated July 26, 1945, it was stated that Japanese sovereignty would be limited only to the islands of Honshu, Hokkaido, Kyushu, Shikoku and other smaller islands, which would be designated by the victorious countries. The Kuril Islands were not mentioned.
After the defeat of Japan, on January 29, 1946, Memorandum No. 677 of the Commander-in-Chief of the Allied Powers, American General Douglas MacArthur, excluded the Chishima Islands (Kuril Islands), the Habomadze group of islands (Habomai) and the Sikotan Island (Shikotan) from Japanese territory.
According to San Francisco Peace Treaty dated September 8, 1951, the Japanese side renounced all rights to South Sakhalin and the Kuril Islands. But the Japanese claim that Iturup, Shikotan, Kunashir and Habomai (islands of the Lesser Kuril Islands) were not part of the Chishima Islands (Kuril Islands) and they did not abandon them.
Negotiations in Portsmouth (1905) - from left to right: from the Russian side (far part of the table) - Planson, Nabokov, Witte, Rosen, Korostovets.
Further agreements
Joint Declaration. On October 19, 1956, the Soviet Union and Japan adopted a Joint Declaration. The document ended the state of war between the countries and restored diplomatic relations, and also spoke of Moscow’s consent to the transfer of the islands of Habomai and Shikotan to the Japanese side. But they were supposed to be handed over only after the signing of a peace treaty. However, later Japan was forced to refuse to sign a peace treaty with the USSR. The United States threatened not to give up Okinawa and the entire Ryukyu Archipelago to the Japanese if they renounced their claims to the other islands of the Lesser Kuril chain.
After Tokyo signed the Cooperation and Security Treaty with Washington in January 1960, extending the American military presence on the Japanese Islands, Moscow announced that it refused to consider the issue of transferring the islands to the Japanese side. The statement was justified by the security issue of the USSR and China.
In 1993 it was signed Tokyo Declaration about Russian-Japanese relations. It stated that the Russian Federation is the legal successor of the USSR and recognizes the 1956 agreement. Moscow expressed its readiness to begin negotiations regarding Japan's territorial claims. In Tokyo this was assessed as a sign of impending victory.
In 2004, the head of the Russian Ministry of Foreign Affairs, Sergei Lavrov, made a statement that Moscow recognizes the 1956 Declaration and is ready to negotiate a peace treaty based on it. In 2004-2005, this position was confirmed by Russian President Vladimir Putin.
But the Japanese insisted on the transfer of 4 islands, so the issue was not resolved. Moreover, the Japanese gradually increased their pressure; for example, in 2009, the head of the Japanese government at a government meeting called the Lesser Kuril Ridge “illegally occupied territories.” In 2010 and early 2011, the Japanese became so excited that some military experts began to talk about the possibility of a new Russian-Japanese war. Only the spring natural disaster - the consequences of a tsunami and a terrible earthquake, the accident at the Fukushima nuclear power plant - cooled Japan's ardor.
As a result, the loud statements of the Japanese led to Moscow declaring that the islands are the territory of the Russian Federation legally following the Second World War, this is enshrined in the UN Charter. And Russian sovereignty over the Kuril Islands, which has the appropriate international legal confirmation, is beyond doubt. Plans were also announced to develop the islands' economy and strengthen Russia's military presence there.
Strategic importance of the islands
Economic factor. The islands are economically underdeveloped, but they have deposits of valuable and rare earth metals - gold, silver, rhenium, titanium. The waters are rich in biological resources; the seas that wash the shores of Sakhalin and the Kuril Islands are among the most productive areas of the World Ocean. The shelves, where hydrocarbon deposits are found, are also of great importance.
Political factor. The cession of the islands will sharply lower Russia’s status in the world, and there will be a legal opportunity to review other results of the Second World War. For example, they may demand that the Kaliningrad region be given to Germany or part of Karelia to Finland.
Military factor. The transfer of the South Kuril Islands will provide the Japanese and US naval forces with free access to the Sea of Okhotsk. It will allow our potential adversaries to exercise control over strategically important strait zones, which will sharply worsen the deployment capabilities of the Russian Pacific Fleet, including nuclear submarines with intercontinental ballistic missiles. This will be a strong blow to the military security of the Russian Federation.
Statement Japanese Prime Minister Shinzo Abe about the intention to resolve the territorial dispute over the Kuril Islands and again attracted the attention of the general public to the so-called “problem of the Southern Kurils” or “northern territories”.
Shinzo Abe's loud statement, however, does not contain the main thing - an original solution that could suit both sides.
Land of the Ainu
The dispute over the Southern Kuril Islands has its roots in the 17th century, when there were neither Russians nor Japanese on the Kuril Islands.
The indigenous population of the islands can be considered the Ainu, a people whose origins are still debated by scientists. The Ainu, who once inhabited not only the Kuril Islands, but also all the Japanese islands, as well as the lower reaches of the Amur, Sakhalin and the south of Kamchatka, have today turned into a small nation. In Japan, according to official data, there are about 25 thousand Ainu, and in Russia there are just over a hundred of them left.
The first mentions of the islands in Japanese sources date back to 1635, in Russian sources - to 1644.
In 1711, a detachment of Kamchatka Cossacks led by Danila Antsiferova And Ivan Kozyrevsky first landed on the northernmost island of Shumshu, defeating a detachment of local Ainu here.
The Japanese also showed more and more activity in the Kuril Islands, but no demarcation line and no agreements existed between the countries.
Kuriles - to you, Sakhalin— us
In 1855, the Shimoda Treaty on trade and borders between Russia and Japan was signed. This document for the first time defined the border of the possessions of the two countries in the Kuril Islands - it passed between the islands of Iturup and Urup.
Thus, the islands of Iturup, Kunashir, Shikotan and the Habomai group of islands came under the rule of the Japanese emperor, that is, the very territories around which there is a dispute today.
It was the day of the conclusion of the Shimoda Treaty, February 7, that was declared in Japan as the so-called “Northern Territories Day”.
Relations between the two countries were quite good, but they were spoiled by the “Sakhalin issue.” The fact is that the Japanese claimed the southern part of this island.
In 1875, a new treaty was signed in St. Petersburg, according to which Japan renounced all claims to Sakhalin in exchange for the Kuril Islands - both Southern and Northern.
Perhaps, it was after the conclusion of the 1875 treaty that relations between the two countries developed most harmoniously.
Exorbitant appetites of the Land of the Rising Sun
Harmony in international affairs, however, is a fragile thing. Japan, emerging from centuries of self-isolation, was rapidly developing, and at the same time its ambitions were growing. The Land of the Rising Sun has territorial claims against almost all its neighbors, including Russia.
This resulted in the Russo-Japanese War of 1904-1905, which ended in a humiliating defeat for Russia. And although Russian diplomacy managed to mitigate the consequences of military failure, nevertheless, in accordance with the Portsmouth Treaty, Russia lost control not only over the Kuril Islands, but also over South Sakhalin.
This state of affairs did not suit not only Tsarist Russia, but also the Soviet Union. However, it was impossible to change the situation in the mid-1920s, which resulted in the signing of the Beijing Treaty between the USSR and Japan in 1925, according to which the Soviet Union recognized the current state of affairs, but refused to acknowledge “political responsibility” for the Portsmouth Treaty.
In subsequent years, relations between the Soviet Union and Japan teetered on the brink of war. Japan's appetite grew and began to spread to the continental territories of the USSR. True, the defeats of the Japanese at Lake Khasan in 1938 and at Khalkhin Gol in 1939 forced official Tokyo to slow down somewhat.
However, the “Japanese threat” hung like a sword of Damocles over the USSR during the Great Patriotic War.
Revenge for old grievances
By 1945, the tone of Japanese politicians towards the USSR had changed. There was no talk of new territorial acquisitions—the Japanese side would have been quite satisfied with maintaining the existing order of things.
But the USSR gave an undertaking to Great Britain and the United States that it would enter the war with Japan no later than three months after the end of the war in Europe.
The Soviet leadership had no reason to feel sorry for Japan - Tokyo behaved too aggressively and defiantly towards the USSR in the 1920s and 1930s. And the grievances of the beginning of the century were not forgotten at all.
On August 8, 1945, the Soviet Union declared war on Japan. It was a real blitzkrieg - the million-strong Japanese Kwantung Army in Manchuria was completely defeated in a matter of days.
On August 18, Soviet troops launched the Kuril landing operation, the goal of which was to capture the Kuril Islands. Fierce battles broke out for the island of Shumshu - this was the only battle of the fleeting war in which the losses of Soviet troops were higher than those of the enemy. However, on August 23, the commander of the Japanese troops in the Northern Kuril Islands, Lieutenant General Fusaki Tsutsumi, capitulated.
The fall of Shumshu became the key event of the Kuril operation - subsequently the occupation of the islands on which the Japanese garrisons were located turned into acceptance of their surrender.
Kurile Islands. Photo: www.russianlook.comThey took the Kuril Islands, they could have taken Hokkaido
On August 22, Commander-in-Chief of the Soviet troops in the Far East, Marshal Alexander Vasilevsky, without waiting for the fall of Shumshu, gives the order to troops to occupy the Southern Kuril Islands. The Soviet command is acting according to plan - the war continues, the enemy has not completely capitulated, which means we should move on.
The initial military plans of the USSR were much broader - Soviet units were ready to land on the island of Hokkaido, which was to become a Soviet zone of occupation. One can only guess how the further history of Japan would have developed in this case. But in the end, Vasilevsky received an order from Moscow to cancel the landing operation in Hokkaido.
Bad weather somewhat delayed the actions of Soviet troops in the Southern Kuril Islands, but by September 1, Iturup, Kunashir and Shikotan came under their control. The Habomai island group was completely taken under control on September 2-4, 1945, that is, after the surrender of Japan. There were no battles during this period - the Japanese soldiers resignedly surrendered.
So, at the end of World War II, Japan was completely occupied by the Allied powers, and the main territories of the country came under US control.
On January 29, 1946, Memorandum No. 677 of the Commander-in-Chief of the Allied Powers, General Douglas MacArthur, excluded the Kuril Islands (Chishima Islands), the Habomai (Habomadze) group of islands, and Shikotan Island from Japanese territory.
On February 2, 1946, in accordance with the Decree of the Presidium of the Supreme Soviet of the USSR, the Yuzhno-Sakhalin Region was formed in these territories as part of the Khabarovsk Territory of the RSFSR, which on January 2, 1947 became part of the newly formed Sakhalin Region as part of the RSFSR.
Thus, de facto, South Sakhalin and the Kuril Islands passed to Russia.
Why didn't the USSR sign a peace treaty with Japan?
However, these territorial changes were not formalized by a treaty between the two countries. But the political situation in the world has changed, and yesterday’s ally of the USSR, the United States, turned into Japan’s closest friend and ally, and therefore was not interested in either resolving Soviet-Japanese relations or resolving the territorial issue between the two countries.
In 1951, a peace treaty was concluded in San Francisco between Japan and the countries of the anti-Hitler coalition, which the USSR did not sign.
The reason for this was the US revision of previous agreements with the USSR, reached in the Yalta Agreement of 1945 - now official Washington believed that the Soviet Union had no rights not only to the Kuril Islands, but also to South Sakhalin. In any case, this is exactly the resolution that was adopted by the US Senate during the discussion of the treaty.
However, in the final version of the San Francisco Treaty, Japan renounces its rights to South Sakhalin and the Kuril Islands. But here, too, there is a catch - official Tokyo, both then and now, states that it does not consider Habomai, Kunashir, Iturup and Shikotan to be part of the Kuril Islands.
That is, the Japanese are sure that they really renounced South Sakhalin, but they never renounced the “northern territories”.
The Soviet Union refused to sign a peace treaty not only because its territorial disputes with Japan were unresolved, but also because it did not in any way resolve similar disputes between Japan and the then USSR ally, China.
Compromise ruined Washington
Only five years later, in 1956, the Soviet-Japanese declaration on ending the state of war was signed, which was supposed to be the prologue to the conclusion of a peace treaty.
A compromise solution was also announced - the islands of Habomai and Shikotan would be returned to Japan in exchange for unconditional recognition of the sovereignty of the USSR over all other disputed territories. But this could happen only after the conclusion of a peace treaty.
In fact, Japan was quite happy with these conditions, but then a “third force” intervened. The United States was not at all happy about the prospect of establishing relations between the USSR and Japan. The territorial problem acted as an excellent wedge driven between Moscow and Tokyo, and Washington considered its resolution extremely undesirable.
It was announced to the Japanese authorities that if a compromise was reached with the USSR on the “Kuril problem” on the terms of the division of the islands, the United States would leave the island of Okinawa and the entire Ryukyu archipelago under its sovereignty.
The threat was truly terrible for the Japanese - we were talking about an area with more than a million people, which has the greatest historical significance for Japan.
As a result, a possible compromise on the issue of the Southern Kuril Islands melted away like smoke, and with it the prospect of concluding a full-fledged peace treaty.
By the way, control over Okinawa finally passed to Japan only in 1972. Moreover, 18 percent of the island’s territory is still occupied by American military bases.
Complete dead end
In fact, there has been no progress in the territorial dispute since 1956. During the Soviet period, without reaching a compromise, the USSR came to the tactic of completely denying any dispute in principle.
In the post-Soviet period, Japan began to hope that Russian President Boris Yeltsin, generous with gifts, would give up the “northern territories.” Moreover, such a decision was considered fair by very prominent figures in Russia - for example, Nobel laureate Alexander Solzhenitsyn.
Perhaps at this moment the Japanese side made a mistake, instead of compromise options like the one discussed in 1956, they began to insist on the transfer of all the disputed islands.
But in Russia the pendulum has already swung in the other direction, and those who consider the transfer of even one island impossible are much louder today.
For both Japan and Russia, the “Kuril issue” has become a matter of principle over the past decades. For both Russian and Japanese politicians, the slightest concessions threaten, if not the collapse of their careers, then serious electoral losses.
Therefore, Shinzo Abe’s declared desire to solve the problem is undoubtedly commendable, but completely unrealistic.
One of the first documents regulating Russian-Japanese relations was the Treaty of Shimoda, signed on January 26, 1855. According to the second article of the treatise, the border was established between the islands of Urup and Iturup - that is, all four now islands that Japan claims today were recognized as the possession of Japan.
Since 1981, the day of the conclusion of the Shimoda Treaty in Japan has been celebrated as “Northern Territories Day”. Another thing is that, relying on the Shimoda Treaty as one of the fundamental documents, Japan forgets about one important point. In 1904, Japan, having attacked the Russian squadron in Port Arthur and unleashed the Russo-Japanese War, itself violated the terms of the treaty, which provided for friendship and good neighborly relations between states.
The Shimoda Treaty did not determine the ownership of Sakhalin, where both Russian and Japanese settlements were located, and by the mid-70s a solution to this issue was ripe. The St. Petersburg Treaty was signed, which was assessed ambiguously by both sides. Under the terms of the agreement, all the Kuril Islands were now completely transferred to Japan, and Russia received full control over Sakhalin.
Then, as a result of the Russo-Japanese War, according to the Treaty of Portsmouth, the southern part of Sakhalin up to the 50th parallel went to Japan.
In 1925, a Soviet-Japanese convention was signed in Beijing, which generally confirmed the terms of the Portsmouth Treaty. As you know, the late 30s and early 40s were extremely tense in Soviet-Japanese relations and were associated with a series of military conflicts of varying scales.
The situation began to change by 1945, when the Axis powers began to suffer heavy defeats and the prospect of losing World War II became increasingly clear. Against this background, the question of the post-war world order arose. Thus, according to the terms of the Yalta Conference, the USSR pledged to enter the war against Japan, and Southern Sakhalin and the Kuril Islands were transferred to the Soviet Union.
True, at the same time the Japanese leadership was ready to voluntarily cede these territories in exchange for the neutrality of the USSR and the supply of Soviet oil. The USSR did not take such a very slippery step. The defeat of Japan by that time was not a quick matter, but it was still a matter of time. And most importantly, by avoiding decisive action, the Soviet Union would actually be handing the situation in the Far East into the hands of the United States and its allies.
By the way, this also applies to the events of the Soviet-Japanese War and the Kuril Landing Operation itself, which was not initially prepared. When it became known about the preparations for the landing of American troops on the Kuril Islands, the Kuril landing operation was urgently prepared within 24 hours. Fierce fighting in August 1945 ended with the surrender of the Japanese garrisons in the Kuril Islands.
Fortunately, the Japanese command did not know the real number of Soviet paratroopers and, without fully using their overwhelming numerical superiority, capitulated. At the same time, the Yuzhno-Sakhalin offensive operation was carried out. Thus, at the cost of considerable losses, Southern Sakhalin and the Kuril Islands became part of the USSR.