In 1993 and 1996 I helped broker understandings that brought conflicts between Hizbullah and Israel to an end. Both times Hizbullah instigated warfare with Katyusha rocket fire into Israel and Israel retaliated, determined to damage Hizbullah's capacity for making war and to demonstrate to the Lebanese the cost of Hizbullah's adventures. And both times, to bring about an enduring cease-fire, we needed to deal with Syria. This time, however, the cease-fire deal was done without the Syrians. The question is: Can the terms of UN Security Council Resolution 1701 be fulfilled without Syria being part of the equation? It doesn't seem likely. Implementation of this resolution will depend to a large degree on the Syrians - unless, of course, the new international force deployed with the Lebanese army can both prevent resupply to Hizbullah and bolster Lebanon's military so it can fulfill the role envisioned for it in the resolution. The more determined Syria is to frustrate implementation of the resolution, the more the international force will need a capability and a mandate to be aggressive in stopping efforts to get arms to Hizbullah and in preventing its restoration as a fighting force. Will the international force have intensive inspection capability? Will it be deployed along all routes into Lebanon from Syria and be able to inspect all relevant vehicular traffic? Will it set up checkpoints on north-south access routes in Lebanon to do the same? And can 15,000 soldiers be organized to perform these roles while also preventing Hizbullah from training and rebuilding its fortifications in the area from the Litani River to the Israeli border? IN THEORY it's possible that the multinational force will be able to meet these challenges. But given how quickly it must be constituted and deployed, there is every reason to believe it will not be able to accomplish such a mission anytime soon. Even in the best case, the forces are not likely to be aggressive if it means disrupting commerce between Syria and Lebanon or depriving Hizbullah of weapons that it seeks. (Already the French foreign minister has declared that he does not foresee disarming Hizbullah.) To be sure, the implementation of the letter and the spirit of the resolution will also depend on the Lebanese government and army. Both institutions remain fragile, and Syrian opposition could exploit ongoing sectarian differences. With the international community ready to bolster the Lebanese government with forces and reconstruction assistance, there has never been a more promising moment for the Lebanese to act on their national obligations. They need to know that assistance, while forthcoming, will be tied over time to their government and their army living up to their responsibilities. But there should be no illusions. History is full of good resolutions on Lebanon that have not been implemented because the Syrians had the power to block them. At a time when Syrian President Bashar Assad is calling Hizbullah's victory a defeat for US plans in the Middle East, and Secretary of State Condoleezza Rice is proclaiming that implementation of Resolution 1701 will constitute a strategic setback for the Syrian regime, can Syria's behavior be altered to make this UN resolution's fate different from those of its predecessors? IT CAN if we take advantage of the new basis that exists to exercise much more leverage on Syria this time. Consider that the French and other Europeans will now be putting forces on the ground in Lebanon. If Hizbullah is being resupplied with arms and can be reconstituted militarily, those forces will become vulnerable. That gives the French a powerful stake in preventing Hizbullah from rearming. Working in tandem, the Bush administration and the French should try to change the Syrian calculus. Syria sees Hizbullah as a card - something to be exploited to make Syria a factor in the region or to be traded in the right circumstances. We should create a one-two punch with the French to make clear that Syria has something significant to lose by not cutting off Hizbullah, and that it has something meaningful to gain from changing course. Surely, if the international force is seen as credible and determined, it can convince Assad that Hizbullah is going to be contained and that its value to Syria could diminish. But Assad must also see that Syria will pay an unmistakable price if it tries toblock implementation of Resolution 1701. That price could be a joint French-EU and American effort to isolate Syria economically if it is unwilling to end its material support for Hizbullah. The Europeans currently provide a critical economic lifeline to the Syrians. French President Jacques Chirac could credibly warn Assad that if arms flow to Hizbullah and threaten French troops, then Europe will cut all economic ties to Syria. Conversely, if Syria ended its military relationship with Hizbullah and accepted the Lebanese government's effort to reestablish its authority, the European Union could promise new and meaningful economic benefits to Damascus. IN SUCH a scenario, the European Union would be Act 1. Act 2 would involve the United States. The Bush administration, which has expressed an interest in weaning Syria away from Iran, won't be able to do that without talking to the Syrians. And it won't be able to do it by continuing to make threats that have no consequences. It will not be enough to continue saying, "The Syrians know what they need to do." The United States must reinforce a tough EU message with one of its own to Assad, namely this: We are prepared to implement a range of sanctions, including the Syrian Accountability Act and executive orders that would make it difficult for companies and financial institutions that do business in Syria to conduct business in the United States. This would have the potential of choking off European, Asian (and even Arab) countries and businesses from having any commercial or investment relations with Syria and it could be devastating for an already weak economy. That's a lever that should be deployed to build the Syrian interest in cooperating. NO DOUBT the Syrians would want to know what they'd get from such cooperation. They should be told that the page can be turned in our relations, that economic benefits could be forthcoming, and that even a resumption of the peace process between Syria and Israel on the Golan Heights could be in the offing. None of these things can be available if Syria is not prepared to cut off Hizbullah and Hamas. Why, after all, would we invest anything in a peace process when those two organizations retain the means - with Syrian support - of subverting that process at a time of their choosing? History is littered with well-intentioned efforts to transform Lebanon. If the current effort is to be different, we will need a credible international force shaped by real, not symbolic, missions and a new approach to Syria - one that gives the Syrians a reason to calculate their interests differently. The writer was director for policy planning in the State Department under President George H.W. Bush and special Middle East coordinator under president Bill Clinton. He is counselor of the Washington Institute for Near East Policy.