The war developed from Russia's and Japan's rivalry for dominance in Korea and Manchuria. After the First Sino-Japanese War, Japan acquired the Liaodong Peninsula from China, but European powers forced Japan to return it. China subsequently leased it to Russia.

The statements are referring to the Russo-Japanese War of 1904-1905.

Explanation:

The Russo-Japanese War was a conflict between Russia and Japan due to the two countries' imperialist aspirations in Asia, especially related to Korea and Manchuria. The war started in February 1904 and ended in September the following year. The land battles were particularly fought over the city of Port Arthur and the Liaodong Peninsula as well as the railway from the port to Harbin.

Russia suffered a series of defeats in the conflict and had to give Japan a number of concessions at the peace treaty, including the control of Korea.

The outcome of the war first led to a major change in the balance of power in East Asia, and opened in the longer term for later Japanese expansion.  Russia abandoned Liaodong and Port Arthur, relinquished the southern half of the island of Sakhalin to Japan, and withdrew from Manchuria. Korea thus remained uncontested in Japan's sphere of interest.  

In a wider sense, the humiliating Russian defeat contributed to the internal tension and dissatisfaction with the Tsar regime in Russia, leading up to the 1905 revolution.

what