What if the United States joined Russia in the Russo-Japanese War and triggered the Anglo-Japanese Alliance?
Short answerIt is an unlikely but potentially vast conflict in which British sea power, trade pressure, and a new naval race matter as much as the initial fighting.
NotesThe United States has no clear reason to support Russia in this scenario, but doing so would likely bring Britain and Japan into the war under their alliance. British intervention would probably stop the Russian reinforcement fleet before it reached East Asia and expose American trade to Royal Navy pressure. The widening conflict then draws in Germany and turns New York, Canada, and maritime supply into strategic problems. Later discussion connects the war to longer-ranged, faster battleships, centreline armament, and separate quantitative and qualitative naval races. The counterfactual tests how alliances, commerce, basing, industrial capacity, and combat experience could turn a regional war into a much larger one.