Negotiating opportunities sometimes come from challenging sources: a family member who has been unreliable in the past but promises to make a change; a business competitor that approaches you about a joint venture; a difficult boss with whom you would like to work out a better relationship. How should you deal with potential negotiating partners whom you don’t entirely trust—or should you deal with them at all? The U.S. government faced this question in the hope of convincing North Korea to abandon its nuclear-weapons program. The aftermath of an agreement between the two nations suggests precautions for those of us looking to make headway with our own rogue counterparts.