Ruled by an emperor but controlled by militarists, Japan — desperate for raw materials — was ready to continue the expansion it had started nearly forty-five years earlier with the acquisition of the island of Burile, the Bonin and Ryukyu Islands, and the Volcano group. In war with China in 1894 and 1895, Japan took Formosa (now Taiwan) and the Pescadores. Soon afterward, it seized Port Arthur and the southern half of the island of Sakhalin from Russia and took control of Korea, which it officially annexed in 1910. After World War I, Japan received mandates over the Marshall, Caroline, and Mariana Islands, which had formerly belonged to Germany.
Following the Naval Disarmament Conference of 1920, which weakened the American and British presence in the Pacific, Japan strengthened its powerful navy, fortified its mandates in violation of international treaty, and set its eyes on China while conditioning its people for the inevitability of war.