So is the Korea's Obama's big chance to show how strong he is and start world war 3?

He would be best served to ask China to stay out of it and agree to as well, and allow the kids to get it all out of their system. If N Korea knows China isn't going to help them they may not be so emboldened to start a fight. S Korea doesn't really want US intervention anyhow, and I believe they understand who and what Obama is......