Were Britain and the United States already naval partners?

Was the United States too non-aligned in the 1920s for close naval cooperation with Britain?

No. Washington avoided European alliances, but the British and American navies cooperated from about 1924 because both expected partnership in a possible Asian war with Japan.

American political avoidance of European alliances did not prevent naval planning in Asia, where both services expected they would probably fight Japan together. Cooperation built from their wartime experience and was underway by about 1924, helping later joint systems appear quickly during the Second World War. Economic competition and political rhetoric continued between the two countries. Neither navy treated active war between Britain and the United States as the likely strategic problem.