The assessment predicts: "Tens or hundreds of thousands could become casualties" ... in the event of an all-out DRPK/(US+ROK) conflict. One factor to consider here is what happens if no conflict occurs? In that case, there are ... still likely tens of thousands of civilian deaths happening as the status quo in North Korean labor camps[1]. Allowing the regime to continue to exist also has a major cost in human lives.…
"Allowing the regime to continue to exist" is a backwards way of looking at things that serves to legitimate invasions. The US is a superpower, but that doesn't mean that other nation-states exist because we deign to suffer their existence—that's a very colonialist way of looking at the world. Invading the north (or provoking it with special operations) would be a positive action for which the US would be responsible…
This is a question of international consensus, not US will. Under the definition of sovereignty agreed upon by the international community, DPRK has forfeited its' right to sovereignty by repeated human rights abuses, WMD development, and aggression toward it's neighbors. Essentially, if a state fails to uphold it's responsibility to its' citizens, sovereignty is forfeited. Admittedly this is a hard thing to judge, but a line must be drawn somewhere.