Would Sakhalin oil have changed Japan's choice for war?

If Japan had found large oil reserves in Sakhalin, might it have avoided war with the United States?

Possibly. A self-sufficient oil supply could have removed the acute vulnerability that made U.S. sanctions such a dangerous trigger for war.

The counterfactual turns on fuel rather than on a different naval battle plan. Domestic oil might have made Japan self-sufficient in the resource it most feared losing and could therefore have reduced the pressure for war. U.S. control over oil access is described as a "golden bullet": once sanctions threatened that supply, American leaders had to anticipate a military response. Domestic reserves would not have solved every problem, but they would have changed the coercive leverage at the centre of the crisis.