In response to this bold bid for regional hegemony, the United States has apparently resolved . . . to intensively negotiate with itself and its chief European allies about how it might "engage" Mr. Ahmadinejad and Mr. Assad. Should a U.S. ambassador return to Damascus, once the uproar over Mr. Gemayel dies down? Should the administration drop its demand that Iran obey a U.N. resolution ordering it to suspend enrichment before talks can begin? While the debate goes on, the Western effort to sanction Iran for its nuclear program is stalled and all but forgotten. No punitive action against Syria is even being discussed. Those most focused on rescuing the Iraq mission -- such as the Baker-Hamilton study group -- are most interested in the engagement option. We, too, have supported including Iran and Syria in a regional diplomatic initiative to promote an Iraqi political accord. But it's vital to keep in mind that such an effort has a low probability of ending the bloodshed in the near future, even if all parties cooperate. What's more, no attempt to reason with Mr. Assad and the Iranian mullahs will succeed unless they perceive that the United States and its allies wield sticks as well as carrots.