The president urged sanctions against North Korea. The U.N. approved the idea. There is some conjecture that enforcing sanctions will be difficult - well, yes, that is the burden.
I've spoken openly several times about how the Chonger was the one that we should have focused our efforts on, not Hussein - primarily based on the fact that he was flaunting his dismissal of IAEA inspectors, continuing with nuclear proliferation, and the 2 million in negative population growth which seems to be less important than some 30K in an oil rich nation.
However, we invaded Iraq, killed anywhere between 400 and 800 thousand civilians (the "official" estimate was 655K, but that had a plus-minus of 200K). We're stuck in Iraq because the people haven't embraced our version of liberty as heartily as we assumed they would, and our continued presence is needed to delay all out civil war. Combine that with our resources commited to putting out the appearance of hunting for OBL, and we simply don't have the resources to overthrow the Chonger's regime. As such, the President's urging of sanctions is probably the next best policy. One might argue that it was the first best policy in Iraq, but it's a moo point now. At any rate, it doesn't seem to make sense to criticize the President for doing now what so many thought he should have in the past.
Now, sanctions must be very tough on North Korea. I think we need to suspend all food aid to the country, no exportation of natural resources, and effectively blockade the country - check all shipping for evidence of arms, contraband, etc.. The country is scarecely hanging on as it is, and it knows that we can't attack at this time. We need to take as many balls out of North Korea's court as possible and force them to move decisively toward explosion or implosion. At this point, there's little more we can do to a nation we've so much as declared an enemy.