Japan began to invade its east asia neighbors during the 19th and 20th centuries in order

secure the natural resources needed for industrialization.

After the Meiji restoration, Japan started many reforms in the country, following western models that included the western imperialism. Japan began to modernize itself in order to create a powerful country with a good economy and a great military power, which it was achieving. After Japan took control over the Ryukyu Islands, back in the 1870s, the rivalry between the countries started. Japan was actually trying to secure natural resources that it needed for industrialization.