Final answer:
The events of the Russo-Japanese War and the Treaty of Portsmouth confirmed Japan's emergence as a major power, expanded its influence in Asia, especially over Korea and Manchuria, and triggered significant internal political changes in Russia.
Step-by-step explanation:
The Russo-Japanese War and the resulting Treaty of Portsmouth had a profound impact on Japan's position in the world. Through its victory, Japan demonstrated the power of an organized and industrialized nation in modern warfare, establishing itself as a formidable military power.
The war also had broader implications, signaling to the world that European powers could be defeated, thereby inspiring colonized peoples towards independence. Japan's influence in Asia expanded significantly, as the Treaty of Portsmouth recognized its authority over Korea and awarded it control over the southern part of Sakhalin Island and influence in southern Manchuria, making it a dominant power in East Asia.
Additionally, Japan's victory led to its formal annexation of Korea in 1910, while for Russia, it precipitated a period of internal strife and discontent that eventually contributed to the 1905 Revolution and political reforms. The United States' role in mediating the peace negotiations highlighted the growing significance of American interests in Asia.