President Bush built a coalition and invaded Iraq, removing a potential threat. Regardless the coalition partners and UNSC resolutions, he was widely condemned as acting unilaterally. What was really being condemned was the implementation of a stated policy of preemption.
President Bush built a coalition and an engaged North Korea in diplomatic negotiations through the six-party talks, allowing the potential threat to grow. (For a great example of this process, read James Kelly's remarks from two years ago. Diplomats certainly can't be considered men of action.) Although "complete, verifiable, irreversable disarmament (CVID) was stated as the goal, some analysts disagreed. They believed our policy was "...aimed to avoid catastrophic failure, not to achieve success..."
It's now obvious that the policy of the United States was to allow the DPRK to conduct a nuclear weapons test. For you non-policy analyst types out there, remember that the policy is always what you do, not what you say the policy is. Kinda like judging people on their actions, not what they say. But I digress...
The interesting question is whether our "unilateral" strategy of preemption is still on the table.
Is our policy to preempt, have a surrogate preempt, or wait for an attack?