Stepping stone, stopping point, or slippery slope?

The November 2013 "interim" nuclear deal between Iran and the "P5+1"--the United States, Russia, China, Britain, France, and Germany--raises challenging questions. Will the initial deal function as a stepping stone toward a more comprehensive deal? Or will it drift into becoming a stopping point that leaves Iran dangerously close to nuclear weapons capability with the sanctions regime in decline? Or will it devolve to a slippery slope that would end up requiring a painful choice for key players between either acquiescing in a nuclear-capable Iran or attacking Iran's nuclear facilities? With Iran and the P5+1 each splintered into contending factions, a successful stepping stone strategy requires converting enough "persuadable skeptics" on each side to forge a "winning coalition" on behalf of a more comprehensive nuclear deal. This supportive group must be strong enough to overcome the potent "blocking coalition" that will oppose virtually any larger, next-stage agreement. The best chance for the interim accord to become a stepping stone to a more valuable deal calls for a two-pronged negotiating strategy with both value-enhancing and cost-imposing elements. The first prong of this s