Also: in the 1980s there was a view of Japan that is similar to the current view of China. That they are invading, buying up everything, taking our jerbs, etc. There are many movies about this, like "Rising Sun", and even "Gung Ho", etc. So back then it was definitely de rigueur to "study your enemy", and that meant to learn about the Japanese. Yes, Sun Tzu is Chinese. However, it was the view that the Japanese revered this book and it was therefore part of who they were/how they think. Knowing what I know now, I actually agree with this in that the thinking in Sun Tzu's work is almost at the "DNA Level" of a Japanese warrior. I would prefer other more Japanese texts, but Sun Tzu cannot be denied.

All of which is to say that Trump could possibly have become enamored of this book in the 1980s, due to this thinking/fashion in that time.