What the 1902 Anglo-Japanese Alliance required

The alliance declared support for the status quo, territorial integrity, and commercial access in China and Korea, despite the imperial realities already shaping both countries. Its central mechanism was conditional: an ally stayed neutral if the other fought one power, but entered the war if an additional power joined the enemy. In practical Far Eastern terms, Japan could fight Russia with greater confidence that France would not intervene without also facing Britain. That threat made the agreement a deterrent intended to preserve peace rather than an automatic promise to join every war. Both governments also perceived an affinity between island powers, and Japan valued access to British technology.