Japan saw the Russian Empire as a more dangerous long-term challenger than the United States or Britain. Britain lay on the other side of the world and had limited reason to contest Japan north of Singapore, while the United States still appeared more distant despite its growing naval presence. Russia already exercised influence in Manchuria and could continue moving toward Japan through continental and island approaches. Its immense scale made mobilization slow but potentially overwhelming once forces arrived. Korea's position and contribution to Japanese food supply therefore placed the peninsula inside a much wider security competition.
Chapter · 53:48-57:10
Russia as Japan's long-term threat
Russian expansion toward East Asia made Korea's position and food supply especially important to Japanese planners.