What event escalated tensions between Japan and the U.S. prior to World War II?

The escalation of tensions between Japan and the United States prior to World War II can be traced significantly to U.S. imperial ambitions in the Pacific region. During this time, the United States was actively expanding its influence, establishing military bases, and pursuing territorial acquisitions which directly threatened Japan's aspirations for regional dominance.

The U.S. establishment of control over the Philippines and Hawaii, along with its forays into territories such as Guam and Samoa, created a perception in Japan that American expansionism could undermine Japan's own imperial goals and security interests. This perception was exacerbated by the U.S. support for China during conflicts and its increasing military presence in the Pacific, which Japan viewed as a significant threat.

This struggle for power and influence in the Pacific ultimately contributed to a climate of hostility and competition, setting the stage for conflict as both nations sought to assert their dominance in the region in the lead-up to World War II.