Each of the shocks of the last 15 years has exposed a different failure in the nonproliferation system – in Iraq, the absurdity of the gentlemen's agreement; in North Korea, the benefits of noncompliance as well as the dangers of diplomatic irresolution; in Libya, the ease and impunity with which the black market in nuclear supplies operated; and in Iran, the legal protections extended to fuel-cycle activities. A new international architecture of nonproliferation, if there is to be one, must address all of these problems.