U.S. President Barack Obama has rejected Vladimir Putin's claim Syrian rebels were responsible for a chemical gas attack last month, but welcomed the Russian president's involvement in the crisis.
In a U.S. television interview broadcast Sunday, Mr. Obama said any deal must include a verification mechanism to ensure Syria gives up all of its chemical weapons capability.
Meanwhile, Secretary of State John Kerry repeated a warning to Syria that the "threat of force is real" if Damascus does not comply with the newly inked agreement.
Kerry issued the warning Sunday during a stop in Jerusalem, where he discussed the new U.S.-Russian plan to rid Syria of its chemical weapons by the middle of next year.
Syria's Minister for National Reconciliation Sunday described the deal as a "victory" for Damascus, won by its Russian allies, that had taken away the pretext for U.S. military strikes.
The main Western-backed Syrian opposition group - the Syrian National Coalition - called for a ban on the use of ballistic missiles and air power by Mr. Assad's forces in addition to the prohibition on chemical weapons.
Syria's key sponsor, Iran, hailed what it called U.S. retreat from "extremist behavior" and welcomed Washington's "rationality." China, which has veto power in the the U.N. Security Council, also welcomed the deal.
The U.S.-Russian agreement, announced Saturday in Geneva, includes a requirement for the Assad government to submit a comprehensive list of such weapons within one week. It calls for the elimination or removal of all chemical weapons material and equipment by mid-2014.
Under the pact, the U.S. and Russia would back a U.N. enforcement mechanism, but its terms are not yet set. Russia has ruled out the use of force as a threat.
During three days of talks, U.S. and Russian officials agreed that Syria currently holds about 1,000 tons of chemical agents and precursors, including sulfur mustard and sarin gas. U.S. officials believe there are about 45 sites where those munitions and related equipment are stored but say Mr. Assad's regime may have moved some of those supplies.
Syrian compliance with the agreement could avert a U.S. military strike in retaliation for the Syrian government's alleged poison gas attack on civilians last month near Damascus.
The United States says it has confirmed that more than 1,400 people died in the attack, and that there is no doubt the Syrian military was responsible. The Assad government contends rebels carried out the gas attack.