The international situation on the eve of the Russo-Japanese War was favorable to Japan and unfavorable to Russia. In 1902, Britain formed an alliance with Japan to support Japan and contain France. On January 6, 1904, Britain promised to provide loans to Japan in the event of war with Russia. The United States also has a particularly positive attitude. In January 1904, the United States sent High Commissioner to the Philippines Tafto to pay a special visit to Japan, instigating Japan to go to war with Russia and pledging to support Japan. U.S. President Roosevelt also said that Japan's victory would make us extremely satisfied. Japan is playing our tricks. He also said that if France and Germany support Russia, Japan will receive assistance from the United States. The United States' support for Japan is also due to the needs of the United States' external expansion. The United States is expanding in the Far East and cannot tolerate Russia's monopolization of the Northeast. The United States also wants to extend its power into the Northeast, squeeze out Russian power, and seize Russian territory in the Far East. The United States once negotiated with Russia to purchase territory in the Far East, but was rejected. Therefore, the United States supports Japan's war against Russia in order to weaken Russia and Japan and open a channel for the United States to invade the Far East.

Russia was relatively isolated on the eve of the Russo-Japanese War and had no de facto allies. Although France has an alliance with Russia, the purpose of France's alliance with Russia is to deal with Germany, so it does not want Russia's power to be placed in the Far East, and France itself will not transfer its troops away from the Vosges Mountains on the Franco-German border. But France was an ally of Russia after all. After the Anglo-Japanese Alliance was concluded, Russia demanded that it also conclude a treaty with France to deal with the Anglo-Japanese Alliance. The result of the Franco-Russian negotiations was only the "Declaration of Independence" issued on March 16, 1902. The French-Russian "Declaration of Independence" stated: In view of the hostility of some countries to France and Russia and the possibility of riots in China, the two governments have the right to take necessary measures to protect their own interests under the above circumstances. This is just a statement with no specific constraints. In fact, France did not give Russia any help in the subsequent Russo-Japanese War. Germany actively provoked the Russo-Japanese War, not only providing financial assistance to Russia, but also providing arms and military technology to Japan, hoping to make huge war profits from the Russo-Japanese War.

From the perspective of military strength, Japan has been preparing for war with Russia for ten years. By 1903, Japan's army and navy expansion plan for war preparations had been largely completed. Japan's main force is 200,000, concentrated in Asia, while Russia's forces are dispersed. Russia has 20 armored gunboats, but most of them are in the Baltic and Black Seas. Britain has warned Turkey not to allow the Russian Black Sea Fleet to pass through the Black Sea Straits, and the British-controlled Suez Canal will not allow the Russian Baltic Fleet to pass. Although Japan only has seven armored ships, they are concentrated in the Pacific. Therefore, in terms of strength comparison on the battlefield, Japan's strength exceeds that of Russia. Before Japan launched the war in July 1903, in order to paralyze Russia and cover up its military offensive, and at the same time to win favorable public opinion, Japan hypocritically proposed negotiations with Russia to discuss the issues of Manchuria and Korea. Japan demands that Russia recognize unconditionally: Japan exclusively occupies Korea, and Russia's rights in Northeast China are limited; Russia demands that Japan unconditionally recognizes that Russia exclusively occupies Manchuria, and Japan's rights in Korea are limited. The two sides argued and the negotiations reached a deadlock. On February 6, 1904, the negotiations broke down.

On February 8, 1904, the Japanese navy suddenly attacked the Russian Pacific Fleet in Lushunkou, China. On the 10th, Japan and Russia declared war on each other. After several fierce battles, the Japanese army captured Lushunkou in January 1905, and defeated the main force of the Russian army near Shenyang in March. On May 27 of the same year, in the Tsushima Strait, the Japanese navy completely wiped out the Baltic Fleet transferred from Europe. At this time, the Russian Revolution of 1905 was reaching its climax. In order to concentrate its efforts on suppressing the domestic revolution, the Russian government hoped to negotiate peace as soon as possible. Japan also spent a lot during the one year and three months of war, spending 1.73 billion yen on military expenditures, nearly half of which was foreign debt. During the land war, Japan also found it difficult to replenish its troops and was worried that the Russian army would turn back to attack and the previous efforts would be wasted. After the naval battle, Japan was unable to fight anymore, so it also wanted to negotiate a peace.

The attitudes of the United Kingdom and the United States have also changed, and they hope that Russia and Japan will negotiate peace. The purpose of Britain's support for Japan was to use the Japanese to weaken Russia, consolidate British interests in the Far East, and at the same time suppress the national liberation movements that broke out in the colonies.

Now that the first two objectives have been achieved, if Japan continues to fight and consumes too much, it will not be possible to use Japan to suppress the revolution in the East (India). Moreover, the situation in Europe also changed at this time, the contradiction between France and Germany became acute again, and the first Moroccan crisis occurred. Britain saw that Germany was its real enemy, and also wanted to pull the weakened Russia over to deal with Germany. France also hopes for peace talks between Japan and Russia in order to bring Russia back to Europe. The United States also wants to stop the Russo-Japanese War. The United States' purpose is to make both Japan and Russia suffer losses and open the way for the United States to invade the Far East. Now this purpose has been achieved. If Japan occupies a large area of ??Russian territory, Japan's strength will increase, which will not be conducive to the United States' influence in the Far East. Expansion of the Far East. In addition, the entire international bourgeoisie was worried that the awakening of the national liberation movements in the East in Asia in 1905 would in turn prompt the re-eruption of the European workers' movement. They were especially afraid that the overthrow of the tsarist autocratic system would directly break out European revolutions. They all hoped for a Russo-Japanese War. Stop and let the Tsar free his hands to strangle the revolution in his own country.

Under the mediation of the United States, Japan and Russia began negotiations on August 9, 1905, and lasted until September 5. The two sides signed the "Portsmouth Peace Treaty" in Portsmouth, a city on the Atlantic coast of the United States. The peace treaty stipulates that Russia recognizes that Japan has special political, economic and military interests in Korea and has the right to take necessary measures to protect and supervise; Russia transferred the territorial waters of Lushun and Dalian and the railway lease rights from Changchun to Lushunkou obtained from China to Japan; Russia ceded the southern part of Sakhalin Island to Japan. Before and after the Japan-Russia negotiations, Japan also made two deals with the United States and Britain and concluded treaties respectively. The United States and Japan signed the "Taft-Katsura Agreement", and the United States recognized Japan's annexation of North Korea. Britain and Japan concluded the Second Treaty of Alliance, and Britain realized its long-cherished wish to consolidate its rule in India with the help of Japan.

The Russo-Japanese War was an imperialist war in which the two imperialist countries, Japan and Russia, re-divided their spheres of influence in the Far East. Tsarist Russia was in a dominant position in the Far East before the war. At the beginning of the 20th century, Russia was on the eve of the bourgeois revolution. Domestic class contradictions and ethnic contradictions were extremely acute. The Tsar wanted to use the victory in foreign wars to divert the attention of the people and consolidate his rule. However, the failure of the war accelerated the outbreak of the 1905 revolution. The war was local, but the United States, Britain, and Germany all intervened behind the scenes. In particular, the United States and Britain supported Japan, provided financial assistance to Japan, and used the hands of others to realize their strategic intentions. The Russo-Japanese War made France see that Russia was stuck in the Far East and could not count on Russia. This prompted France to coordinate colonial conflicts with Britain and accelerated the conclusion of the Anglo-French Entente.

The Russo-Japanese War was fought on Chinese territory, and the treaty concluded after the war also used the lease and transfer of Chinese territory to reach a compromise between the two imperialist countries. Although Russia was a defeated country, it did not cede territory or pay compensation except for the southern part of Sakhalin Island. The real victims of the Russo-Japanese War were China and North Korea. During the Russo-Japanese War, although the Qing government was corrupt and strictly adhered to neutrality, the Chinese people showed their hatred for the two imperialisms of Japan and Russia. After the Russo-Japanese War, Japan, Russia, Japan, the United States, and Japan and Britain signed treaties respectively to divide the sphere of influence in the Far East. Japan's international status has been greatly improved. Japan controlled North Korea and greatly strengthened its power in the Northeast. Japan occupied the southern part of Sakhalin Island, which was a threat to Vladivostok, Russia's important port in the Far East.

The Russo-Japanese War weakened Russia. After the Russo-Japanese War, Russia returned to the Near East, and the conflict between Germany and Austria for the sphere of influence in the Near East intensified. The development of contradictions between Britain and Germany and Russia and Austria accelerated the conclusion of the Anglo-French Entente and the Anglo-Russian Entente.