Going to detour this into something similar, since the original thread died down -
What's the latest possible PoD for the Japanese to avoid war with the US? Coming to terms with Chiang Kai-shek at some point, to avoid the embargo? Presumably the IJA regards this more as an opportunity to resupply and prepare for Round Two, but if Germany has rolled over France by then, Britain might be willing to throw China under the bus if it meant avoiding a Pacific theater, and so no embargo when Japan attacks China again.
I'm not going to guess on the chances, but IMO you could do it into 1941. The Anti-Comintern Pact being broken by the Molotov-Ribbentrop deal, if played on a bit better by U.S. diplomats, might have kept Japan from thinking she was on the right side. Not demanding "surrender" of Chinese territory, or more clearly saying the U.S. was willing to agree to Japanese control of Manchuria, would be another place (& IMO Chiang would go along with that--if not in the long term...)
You do need to address the "government by assassination", & the cowboy Colonels in the Kwantung Army. (A few public executions of troublemakers?) How likely that is, IDK; it doesn't seem like the odds are good.
If Japan doesn't see herself so closely aligned with Germany, occupying all of IndoChina doesn't happen, & doesn't provoke the U.S. embargo(es).
Come to that, just not slapping on a total oil embargo, & just one on avgas & such (to put a crimp in war fighting), like FDR wanted, might do it.
Would these (all? any?) absolutely prevent war? Maybe not. They'd mostly stall it, & then all bets are off.
