Go back far enough to the attempted intervention of various powers into the Russian Civil War. Instead of eventually withdrawing due to diminishing returns, have the confused, constantly switching priorities regarding the intervention double down on attempting to finally solve their so-called "Northern Problem" and force a Siberian buffer state into being. Depending on how stubborn you make them in that scenario, you'd have an Imperial Japan mired in commitments to the Asian mainland and saddled with the burden of holding restive Siberian territory and trying to financially and militarily prop up their buffer state. In addition to that, have them still try to pursue their ambitions in China, Korea, and Southeast Asia.
The resulting shitshow might just make them cautious about opening hostilities with the US when they're too tied down on the mainland.