By the early twentieth century, the transformation of Japan to a modernized, industrialized nation was complete. The next step in its evolution was imperialism. Japan already had a foot in China after defeating Russia in the Russo-Japanese War (1905). Japan, needing raw materials and a trading partner, invaded resource rich Manchuria in 1931 with imperialist intent (Gordon). In 1937, a skirmish with Chinese troops at the Marco Polo Bridge led to a full-fledged war with China. This was the beginning of World War II in Asia (Mitter). The war ended in 1945 with Japan’s defeat after the U.S. dropped atomic bombs on Hiroshima and Nagasaki.