A Japan-first war could deter Germany through coalition strength

What changes if the Second World War begins with Japan rather than Germany?

An early Pacific war could create an Anglo-American-French-Dutch coalition strong enough to make German intervention much riskier.

British ships had repeated confrontations with Japan before the European war, making a Pacific crisis plausible in contemporary planning. If Japan attacked first, Britain, the United States, France, and the Netherlands could already be cooperating at sea and mobilizing supply systems. Germany would then face opponents on a war footing instead of isolated states still trying to coordinate. Joining Japan by attacking in Europe would amount to confronting a mature four-power coalition, which could alter Berlin's calculation. The order in which crises become wars can reshape alliance credibility.