Sanctions are an act of war. I'm not some bloodthirsty lunatic trying to provoke wars, so no. Why should we impose harsher famine on North Korea's populace? They're communists, keep in mind, so despite their rhetoric of equality, the economic pains and pressures you would try to levy on them would fall on everyone EXCEPT the government (because they are "more equal than others"). You'll just be applying further burden to their oppressed citizenry. That hardship will not inspire open rebellion because they have a national narrative of an imperialist America that one day is going to come back to try to finish the job - and you're playing right into it!