Japan wanted to expand their influence and gain more resources to challenge the West in Asia and establish themselves as the new Pacific and Asian power.
Explanation:
After Japan adopted a westernized military and became heavily industrialized, they lacked the proper resources to produce things like guns, ships, planes, artillery, tanks, etc. Japan also felt threatened by the West given Japan's proximity to their colonies, and felt threatened as an Asian and Pacific power and wanted to become the new Asian power. Japan first needed resources to produce equipment to challenge the West's power in Asia. They declared war on China in 1937 after staging the Marco-polo bridge incident and began spearing into China, hoping to find resources and labor. As the UK was distracted by war in Europe and the French and Dutch collapsed, Japan thought they could swipe their colonies from them knowing they're undefended. These South East Asian colonies were rich in rubber and oil like Malaya and Indonesia. Japan's endgame here was to defeat China, take the resource-rich Western colonies, and establish themselves as the new Pacific and Asian power.
