B-65 large cruisers and the Allied response

How useful would Japan's planned B-65 large cruisers have been if four entered service?

Their speed, range, and nine 12.2-inch guns would make them capable ships and likely increase pressure on the United States to build Alaskas and on Britain to consider a comparable design.

The answer highlights a balanced combination of heavy cruiser-killing armament, useful endurance, and high speed. Four such ships would matter not only through their own operations but through the responses they provoke, strengthening the case for the Alaska class and perhaps a British large cruiser. That makes B-65 a useful example of how an unbuilt design can alter force planning on both sides.