The interwar US-Royal-Japanese naval triangle

Was the US Navy more concerned by Royal Navy or Japanese construction after World War I?

Japan was the likely enemy, but British building set the qualitative benchmark that Japan would answer and therefore indirectly shaped American requirements.

The United States and Britain used one another as demanding war-gaming standards because each represented the strongest possible naval challenge, even though neither expected an actual war. Operational exercises, by contrast, focused more on Japan, whose ratio strategy and Pacific position made it the probable threat affected by every Anglo-American design move.