That's just not true though. We are much stronger than we used to be! We not only have incredible amounts of nukes, but we also have much better technology(planes, guns, boats, all of those are what I mean by technology..)! To even think about starting a war with us is insane!

Well, they really aren't much when compared to the US. Not only are we bigger, but we have much better technology.

To be clear, China only backs North Korea if they are provoked into war, since North Korea is doing this all on their own, they lose Chinas help.

There are a few problems with what you said.

First, we have enough nukes to turn all of North Korea into a barren wasteland easily, so the first Korean War wouldn't be a good indicator of how we would do now. Also, our military is much stronger than it used to be, so there's that.

Second, China would be incredibly stupid to join in a war against the US as they get most of their raw materials from Australia, an ally of the US.