Different opinions still exist as to who blew up the Japanese railroad at Mukden. Strong evidence points to young officers of the Japanese Kwantung Army having conspired to cause the blast, with or without direct orders from Tokyo. Post-war investigations also stated that the original bomb planted by the Japanese failed to explode and a replacement had to be planted. The resulting explosion enabled the Japanese Kwantung Army to accomplish their goal of invading Manchuria and the subsequent establishment of the puppet state of Manchukuo.
The "9.18 Incident Exhibition Museum" at Shenyang, opened by the People's Republic of China on September 18, 1991, takes the position that the explosives were planted by Japan. However, the Yūshūkan museum, neighboring Yasukuni Shrine in Tokyo, places the blame on Chinese militias. Yūshūkan has been criticized for historical revisionism.
David Bergamini's book Japan's Imperial Conspiracy (1971) has a detailed chronology of events in both Manchuria and Tokyo surrounding the Mukden Incident. Bergamini concludes that the greatest deception was that the Mukden Incident and Japanese invasion were planned by junior or hot-headed officers, without formal approval by the Japanese government. Bergamini contends that Emperor Hirohito had approved the plan himself. However, historian James Weland has concluded that senior commanders had tacitly allowed field operatives to proceed on their own initiative, then endorsed the result.
In August 2006, the Yomiuri Shimbun, Japan's top-selling newspaper, published the results of a year-long research project into the general question of who is responsible for the "Showa war". With respect to the Manchurian Incident, the newspaper blamed ambitious Japanese militarists, as well as politicians who were impotent to rein them in.