No US entry in 1917 reshapes the interwar Pacific

Does the Second World War still occur if the United States stays out of the First World War?

Probably, but a more isolationist United States could remove the Washington treaty system and produce very different British, American, and Japanese alignments in the Pacific.

The answer argues that the unresolved First World War settlement still leaves Europe vulnerable to another conflict, while American absence changes the naval world more radically. Without Washington-era arms control, Britain, the United States, and Japan enter the interwar years with different fleets and incentives. A Pacific war might even create an Anglo-American alliance earlier, although a surviving Anglo-Japanese alliance opens a very different path.