After days of intense negotiations, the United States and Russia reached agreement Saturday on a framework to secure and destroy Syria's chemical weapons by mid-2014 and impose U.N. penalties if the Assad government fails to comply.
The deal, announced by U.S. Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov in Geneva, includes what Kerry called "a shared assessment" of the weapons stockpile, and a timetable and measures for Syrian President Bashar Assad to follow so that the full inventory can be identified and seized.
The U.S. and Russia agreed to immediately press for a U.N. Security Council resolution that enshrines the chemical weapons agreement under Chapter 7 of the U.N. Charter, which can authorize both the use of force and nonmilitary measures.
President Barack Obama made clear that "if diplomacy fails, the United States remains prepared to act."
Russia, which already has rejected three resolutions on Syria, would be sure to veto a U.N. move toward military action, and U.S. officials said they did not contemplate seeking such an authorization.
"The world will now expect the Assad regime to live up to its public commitments," Kerry told a packed news conference at the hotel where negotiations were conducted since Thursday night. "There can be no games, no room for avoidance or anything less than full compliance by the Assad regime."
It was not immediately clear whether Syria had signed onto the agreement, which requires Damascus to submit a full inventory of its stocks within the next week. Russia does have a close relationship with Syria and holds influence over its Mideast ally.
Kerry and Lavrov emphasized that the deal sends a strong message not just to Syria but to the world, too, that the use of chemical weapons will not be tolerated.
Lavrov added, cautiously, "We understand that the decisions we have reached today are only the beginning of the road."
The deal is considered critical to breaking the international stalemate blocking a resumption of peace talks to end the Syrian civil war, now in its third year.
Under the framework agreement, international inspectors are to be on the ground in Syria by November. During that month, they are to complete their initial assessment and all mixing and filling equipment for chemical weapons is to be destroyed.
The deal calls for all components of the chemical weapons program to be removed from the country or destroyed by mid-2014.
"Ensuring that a dictator's wanton use of chemical weapons never again comes to pass, we believe is worth pursuing and achieving," Kerry said.
Noncompliance by the Assad government or any other party would be referred to the 15-nation Security Council by the Organization for the Prohibition of Chemical Weapons. That group oversees the Chemical Weapons Convention, which Syria this week agreed to join.
The group's director-general, Ahmet Uzumcu, spoke of adopting "necessary measures" to put in place "an accelerated program to verify the complete destruction" of Syria's chemical weapons, production facilities and "other relevant capabilities."
The U.S. and Russia are two of the five permanent Security Council members with a veto. The others are Britain, China, and France.
"There is an agreement between Russia and the United States that non-compliance is going to be held accountable within the Security Council under Chapter 7," Kerry said. "What remedy is chosen is subject to the debate within the council, which is always true. But there's a commitment to impose measures."
Lavrov indicated there would be limits to using such a resolution.
"Any violations of procedures ... would be looked at by the Security Council and if they are approved, the Security Council would take the required measures, concrete measures," Lavrov said. "Nothing is said about the use of force or about any automatic sanctions."
Kerry spoke of a commitment, in the event of Syrian noncompliance, to "impose measures commensurate with whatever is needed in terms of the accountability."
The agreement offers no specific penalties. Given that a thorough investigation of any allegation of noncompliance is required before any possible action, Moscow could drag out the process or veto measures it deems too harsh.
Kerry stressed that the U.S. believes the threat of force is necessary to back the diplomacy, and U.S. officials have Obama retains the right to launch military strikes without U.N. approval to protect American national security interests.
"I have no doubt that the combination of the threat of force and the willingness to pursue diplomacy helped to bring us to this moment," Kerry said.
But a leading U.S. senator expressed concerns that without the threat of force, it's not clear "how Syrian compliance will be possible under the terms of any agreement."
Republican lawmaker Bob Corker of Tennessee said Syria's "willingness to follow through is very much an open question" and he did not want the negotiations to signal a "retreat from our broader national interests," including support for "moderate" opposition forces in Syria.
Under the deal, the U.S. and Russia are giving Syria just one week, until Sept. 21, to submit "a comprehensive listing, including names, types and quantities of its chemical weapons agents, types of munitions, and location and form of storage, production, and research and development facilities."
International inspectors, the U.S. and Russia agreed, should be on the ground in Syria by November and complete their initial work by the end of the month. They must be given "immediate and unfettered" access to inspect all sites.
Kerry said the two sides had come to agreement on the exact size of Syria's weapons stockpile, a sticking point.
U.S. officials, speaking on condition of anonymity because they were not authorized to publicly discuss details of the negotiations, said the U.S. and Russia agreed that Syria had roughly 1,000 metric tons of chemical weapons agents and precursors, including blister agents, such as sulfur and mustard gas and nerve agents like sarin.
These officials said the two sides did not agree on the number of chemical weapons sites in Syria.
U.S. intelligence believes Syria has about 45 sites associated with chemicals weapons, half of which have "exploitable quantities" of material that could be used in munitions. The Russian estimate is considerably lower; the officials would not say by how much.
U.S. intelligence agencies believe all the stocks remain in government control, the officials said.
U.N. inspectors are preparing to submit their own report this weekend. Secretary-General Ban Ki-moon said Friday that he expected "an overwhelming report" that chemical weapons were indeed used on the outskirts of Damascus on Aug. 21.
A U.N. statement said Ban hoped the agreement will prevent further use of such weapons and "help pave the path for a political solution to stop the appalling suffering inflicted on the Syrian people."
Britain's foreign secretary, William Hague, said Saturday's development was "a significant step forward." Germany said that "if deeds now follow the words, the chances of a political solution will rise significantly," Foreign Minister Guido Westerwelle said.
Obama called for a limited military strike against Assad's forces in response, then deferred seeking congressional approval to consider the Russian proposal.
The commander of the Free Syrian Army rebel group, Gen. Salim Idris, told a news conference in Turkey that the Russian initiative would "buy time" and that rebels will continue "fighting the regime and work for bringing it down."
He said that if international inspectors come to Syria in order to inspect chemical weapons, "we will facilitate their passages but there will be no cease-fire." The FSA will not block the work of U.N. inspectors, he said, and the "inspectors will not be subjected to rebel fire when they are in regime-controlled areas."
Idris said Kerry told him by telephone that "the alternative of military strikes is still on the table."