What was japan's strategy in attacking pearl harbor

Strategy is the script nations write for themselves that dictates subsequent policy and plans. Japan's pre-eminent interest after World War I was to expand and preserve economic hegemony in East Asia, principally China. But to fulfill that strategic aim, Japan would face opposition from colonial powers in the region and from the United States, which sought to maintain an economic "Open Door" in China and protect its island possessions. In the years prior to Pearl Harbor, Japanese-American relations were marked by confrontations over Japanese expansion into China, the seizure of Manchuria, and a buildup of naval forces and facilities in the Pacific.

Japan's naval strategy closely followed its national aims. It envisioned a two-part mission: support operations to expand to the south into Southeast Asia and the Netherlands East Indies, while protecting the Home Islands from an expected attack by the U.S. Pacific Fleet, which might threaten Japan directly or its commercial supply routes.