Again, if the North used chem and bio weapons, they are putting our nukes on the table. And with the really advanced CIA / NSA satellites we have in orbit with thermal imaging that can also detect metal from natural ground clutter, I don't think the North could have many truly undetected atrillery pieces. But the bottom line is, it is extremely unlikely that North Korea would launch a strike against the South, and our people there, even if we shot down a test missile launch of theirs. They know they would lose. It's far more likely that China would force us into a confrontation over Taiwan, than it is that North Korea would decide to give up their soverignty and be forcably re-unified with South Korea, which is going to happen someday anyway. You can't keep the same people apart forever. And there are far more people in the north that want to join with the south, than the other way around.