Japan's reasons for expansion refer to the motivations behind its imperialist ambitions in the late 19th and early 20th centuries, driven by a desire for natural resources, national prestige, and military power. This quest for expansion was rooted in the country's rapid industrialization and the need to secure resources to fuel its economy, as well as a belief in its superiority and a desire to compete with Western powers. These factors contributed significantly to the tensions that eventually led to World War II.