The Anglo-Japanese Alliance was not yet formal, but the relationship supporting it already existed. Commodore Matthew Perry's forced opening of Japan had also left a hostile memory of the United States. Japan's fleet was not enormous, yet even a modest contribution could reinforce the Royal Navy's China Station for operations across the Pacific. That combination would increase pressure on the American West Coast and divide a US Navy already facing threats in the Caribbean and around its island possessions.
Notable Point · 1:04:38-1:05:52
Japan and the Pacific war opportunity
Pre-alliance Anglo-Japanese ties and resentment of Commodore Perry give Japan reasons to join British Pacific operations against the United States.