The South tried that already. We lost 250,000 men and most of our land was destroyed. And, that was before the U.S. had tanks and other fun toys.
Yep. There is no way a secession could happen in this country now. We could give 'em some grief and perhaps a compromise could be reached, but it would be impossible to actually secede and take the land with us to form another country. This country, and the U.N. are too powerful and would not allow it.