This situation is strictly the consequence of the Kim Jong-il regime's disastrous policies. Difficult as it is, I do not believe the U.S. should provide assistance to North Korea. Instead, given North Korea's exceptional history of provocative or worse behavior, any U.S. assistance should be tied to concrete improvements in North Korea's conduct. The U.S. could work with China to work out an arrangement with China serving as a "guarantor" of sorts given China's greater leverage over North Korea and China's interests in stability there. North Korea would be more willing to honor commitments it makes to China than it has with respect to commitments made to the wider international community.
Also, "regime change" via military operations is not viable. Given North Korea's small nuclear arsenal and North Korea's repeated threats to decimate Seoul, the cost-benefit calculus is against such an operation. The U.S. will not pursue a course of action that inflicts catastrophe on South Korea and its people. It also would not pursue a situation that would exacerbate regional risks.
Containment and deterrence are the only practical tools available until North Korea pursues domestic changes on its own that can create a new situation. Even as such a course would require a lot of patience and discipline (e.g., refraining from the emotional impulse to avoid linkage between any kind of aid to North Korea and North Korea's conduct--the U.S. is not pursuing linkage at this time and North Korea will likely "pocket" the humanitarian aid that it receives and maintain its provocative conduct), it is a course that is probably the best of many imperfect or worse options that currently exist.