Background: The Mukden Incident of September 18, 1931, known in Japanese as the Manchurian Incident, occurred in southern Manchuria when a section of railroad, owned by Japan's South Manchuria Railway, near Mukden (today's Shenyang) was dynamited by Japanese junior officers. Imperial Japan's military accused Chinese dissidents of the act, thus providing a pretext for the Japanese occupation of Manchuria. The incident represented an early event in the Second Sino-Japanese War, although full-scale war would not start until 1937.
Answer The Great Depression was one major factor that led to the Japanese' invasion of the north-east state of China, soon to become known as Manchukuo - an independent puppet-run state by the Japenese army. For Japan, its economy was shattered by the collapse of the American market and the subsequent trade tarrif increases by its neighbouring countries, China and the USA. This meant Japan was unable to export any of its goods. In 1931 an incident in Manchuria gave the Japanese army leaders the opportunity they had been looking for to expand its Japanese empire. Manchuria already had a section of Japan-built railway through Manchuria which army leaders claim the Chinese had sabotaged. The occupation of the state was met with little resistance as the Japanese army clearly orchestrated the attack well which suggests today that the incident was pre-empted. The civil government in Tokoyo called for the army to withdraw, but instructions were ignored. This made it clear that it was the army and not the government in control of Japan's foreign policy. Soon the Japanese had access to China's former Manchurian province's natural resources and materials to transport via the railway back.