I didn't mean that China, Japan, and Korea would have a three way war. I meant that all three of them are too rich to risk war over islands and bad history.

The economies that fought in the Second World War were all "modern economies." Europe fought major conflicts every decade or so when they were the "modern economies" of the world.

Modern for what? The 1940s? The economies in the 1940s were nowhere near as interconnected as they are now, and that war is the reason modern economies won't have all out war with each other anymore. They have way too much to lose.

Yes, a hard assessment of U.S. interests might say that something else is more important than a war involving a billion people. But it is hard to say what that would be. A war involving just North vs. South Korea would create substantial risks to basic things like "where do we get cell phones." I happen to think that nations that can contribute to a peaceful, prosperous world order have a moral obligation to do so.

There's no way I'd be willing to interfere in a East Asian war to keep our electronics prices low. But, that doesn't matter because there's no way any of those countries would risk the ability to sell us those electronics by having a war against each other.

I happen to think that nations that can contribute to a peaceful, prosperous world order have a moral obligation to do so.

The region is already peaceful. China and South Korea could both easily crush any trouble North Korea causes. Having Americans there is overkill. America isn't in East Asia to "keep the peace". America is in East Asia because China is our biggest economic rival and "protecting our allies" is a great excuse to use to prevent China from expanding its economic sphere of influence.