What this article misses is that the US "private planes" were being sold directly to Japan and then being converted into military aircraft. What we didn't sell we licensed the designs directly to them.

This went on well into the late 1930s. It was recognized as a potential problem by some but the profits were large enough that these were ignored.

I encourage everyone to read the book "Human Smoke." It is a collection of headlines and newspaper excerpts from the period surrounding WW2. It's a fascinating read and wonderfully exposes all the propaganda driven half truths and complete fabrications we've sold ourselves about the conflict ever since it ended.