Answer: Imperialism.
Step-by-step explanation:
Japanese imperialism was most evident in the late 19th and early 20th centuries, until World War II. That was the reason the Japanese were continuously arming themselves. Japan sought to achieve its imperialist aspirations to the detriment of its neighbors, and for a long time was the most powerful factor in the Far East. By the above, Japan fought during the Second World War on the side of Germany precisely because of its efforts to implement its imperialist aspirations through war.