The Kwantung Army was an army group of the Imperial Japanese Army from 1919 to 1945. The Kwantung Army was formed in 1906 as a security force for the Kwantung Leased Territory and South Manchurian Railway Zone after the Russo-Japanese War, and was expanded into an army group during the Interwar period to support Japanese interests in China, Manchuria, and Mongolia. The Kwantung Army became the most prestigious command in the Imperial Japanese Army, and many of its personnel were promoted to high positions in the Japanese military and civil government, including Hideki Tōjō and Seishirō Itagaki. The Kwantung Army was largely responsible for the creation of the Japanese puppet state of Manchukuo and was one of the main Japanese fighting forces during the Second Sino-Japanese War from 1937.