After the defeat of Russia, Japan focused on the expansion of its empire, beginning with

After defeating Russia in the Russo-Japanese War (1904–1905), Japan strengthened its control over Korea, making it a protectorate in 1905 and annexing it in 1910. This makes “seizing the Korean peninsula and eventually annexing it” the correct choice. Japan had acquired Formosa (Taiwan) earlier, in 1895, after the First Sino-Japanese War.

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