In the last decades of the nineteenth century, Japan emerged from isolation. It began industrializing and modernizing. Japan also had territorial ambitions on the mainland of East Asia. Meanwhile, Russia was also becoming more involved in East Asia. In 1898 they signed a lease with China for a warm-water port, and began building a base they called Port Arthur. Japan saw Russia as a threat. The Japanese proposed each country carve up a sphere of influence in East Asia. Russia would dominate Manchuria, and Japan would dominate Korea. By 1904, the partitioning sparked a war. Historian John Schmidt shares how that war might have had a ripple effect to cause the Pearl Harbor attacks.