Final answer:
The Japanese captured territories in the Pacific to secure critical resources like oil and to create the Greater East Asia Co-Prosperity Sphere, furthering their imperial control and strategic military interests.
Step-by-step explanation:
During the 1930s and 1940s, the Japanese empire sought to capture territories in the Pacific for two primary reasons. Firstly, resource acquisition was crucial for sustaining its war efforts, particularly against China. The Japanese needed oil, rubber, and tin, resources abundant in Southeast Asia but lacking in Japan, and the fall of European colonial powers during World War II presented an opportunity to seize these materials. To secure access to these materials, Japan advanced into French Indochina and the Dutch East Indies.
Secondly, the Japanese aimed to establish a sphere of influence known as the Greater East Asia Co-Prosperity Sphere, a front for their imperial ambitions which also involved overturning Western colonial rule and expanding their control over Asia. To this end, Japan set up puppet regimes and systematically exploited captured territories, such as the Philippines, for their resources. Furthermore, strategic considerations such as countering the threat posed by the U.S. Pacific Fleet, contributed to their aggressive expansion, as evidenced by the surprise attack on Pearl Harbor.
Military strategy and securing a dominant position in Asia were also vital. The Japanese military justified their conquests with the pretext of liberating Asian territories from European colonialism, even as they established their imperial control over these regions.