Kerry said "if fully implemented", the deal could pave the way to a political solution for Syria to be negotiated at a conference which the Russians hope can be organised in October.
Kerry and Lavrov are to confer on September 28 with UN envoy Lakhdar Brahimi in New York on prospects for the conference. UN Secretary-General Ban Ki Moon is due tomorrow to brief the UN Security Council on a report by UN inspectors who investigated the attack that killed up to 1400 people, although they were not asked to identify those responsible. Their report would show "overwhelming" evidence that chemical weapons were used, Ban has said. But the US and Russia continue to disagree on whether it was carried out by regime forces, as contended by Western intelligence, or Syrian rebels, as alleged by the Kremlin.
Chemical weapons expert Dr Jean Pascal Zanders said the stringent US-Russian proposals were "doable". "But it would require diplomatic and legal inventiveness to address certain issues," he added.
The Free Syrian Army reacted bitterly to the Geneva plan, accusing Russia of engaging in delaying tactics on behalf of the Assad regime, and vowed to continue the insurgency.
Dismantling Syrian chemical weapons during a civil war is a unique disarmament challenge. But Kerry said it was "achievable" because of the "extraordinary pains" taken by Assad to secure the chemical arsenal which was "predominantly" in areas controlled by the regime.
Mindful of the experience of the UN weapons inspectors in Iraq, whose government set up an elaborate concealment mechanism, the joint declaration calls for "immediate and unfettered access" to any and all sites in Syria. It provides for the UN Secretary-General to "submit recommendations" regarding the UN role in eliminating the Syrian chemical weapons programme.
The disarmament process is to be backed by a UN Security Council resolution. Chapter VII of the UN Charter, which provides for enforcement measures including military action or sanctions, would be invoked in the event of non-compliance "by anyone in Syria," according to the joint text issued.
"There can be no room for games ... or anything less than full compliance by the Assad regime," Kerry said. He declined to specify what kind of punitive action might be ordered by the Security Council - where Russia has veto power - saying that it would depend on the form of Syrian defiance. But Lavrov stressed that the agreement would avert a "military scenario which would have been catastrophic for the region and international relations as a whole".
Zanders said he could imagine the possible establishment of a separate body of inspectors similar to the UNSCOM operation which took two years to destroy 700 tonnes of Iraqi chemical weapons agents in the 1990s. UN diplomats noted that techniques had evolved since the UNSCOM days, and inspectors now had mobile incineration units at their disposal.
The dismantling of Syria's mustard gas and lethal nerve agents would be on a tight schedule, if approved by the Organisation for the Prohibition of Chemical Weapons (OPCW) which is to act on the US and Russian proposals.
Kerry was effusive in his praise of Russian President Vladimir Putin for his "willingness" to pursue the idea of placing the Syrian weapons under international control.
While the Russian co-operation has provided Obama with a face-saving alternative to ordering military strikes on Syria, it remains to be seen whether Putin can persuade the Syrian Government to comply. Until last week, when the Assad regime announced it would join the Chemical Weapons Convention and detail its stockpile within a month, Damascus had refused to acknowledge holding any toxic gases.
Syria's chemical weapons: the Geneva plan
Points of agreement
*The US and Russia agree to work together on a UN Security Council resolution that would ensure verification of the agreement to secure and destroy Syria's chemical weapons stocks and remove its capability to produce such weapons. The resolution would come under Chapter 7 of the UN charter, which allows for military action. But US officials acknowledge Russia would veto such a step and they do not contemplate seeking authorisation for the use of force. US officials stress that President Barack Obama retains his right to conduct military strikes to defend American national security interests in the absence of UN authorisation.
*The US and Russia give Syria until September 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".
*The US and Russia agree that international inspectors should be on the ground in Syria by November. They must be given "immediate and unfettered" access to inspect all sites. The destruction of chemical agent mixing and filling equipment must be completed by the end of November.
*The US and Russia agree that all of Syria's chemical weapons stocks, material and equipment must be destroyed by mid-2014.
Unresolved issues
*There is not yet any indication that the Assad Government will sign off on the details of the agreement.
*Although they accept that Syria has about 1000 tonnes of chemical weapons and precursors, the two sides have not agreed on the number of sites where they are manufactured and stored. The US says there are roughly 45 sites.
*Details about the composition of the inspection teams and their security must still be determined. The Organisation for the Prohibition of Chemical Weapons, which technically is in charge of the inspections, has never mounted an operation as complex as this and will require assistance from outside parties to conduct the work.
*No specific penalties for Syrian noncompliance have been agreed. Those will be left to the Security Council.
- AP