Jim Woolsey & Gen Tom McInerney in the Wall Street Journal:

Unfortunately, the reflexive rejection in the public debate of the use of force against North Korea has begun to undermine U.S. ability both to influence China to act and to take the preparatory steps necessary for effectiveness if force should be needed. The U.S. and South Korea must instead come together and begin to assess realistically what it would take to conduct a successful military operation to change the North Korean regime.
It is not reasonable to limit the use of force to a surgical strike destroying Yongbyon. Although the facility would need to be destroyed, the possible existence of another plutonium reprocessing plant or of uranium-enrichment facilities, or of plutonium hidden elsewhere, makes it infeasible to limit the use of force to such a single objective. Moreover, military action against North Korea must protect South Korea from certain attack (particularly from artillery just north of the DMZ that can reach Seoul). In short, we must be prepared to win a war, not execute a strike.