The deal struck by the United States and Russia on Saturday that would eliminate Syria's stockpile by next year represents a major advance in easing international controversy over the issue, even while considerable obstacles remain, experts said.
"The deal is a very significant breakthrough given where we were just about a week ago," said Daryl Kimball, executive director of the Arms Control Association, a D.C.-based arms control group. "I'm impressed by the accelerated timelines, which are important here, by the aggressive destruction schedule for Syria's chemical weapons."
The deal was announced after three days of talks in Geneva between Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov. It requires that Bashar Assad's regime make a full accounting of its chemical weapons stockpile within a week. The plan lays out a road map to the elimination of Syria's chemical weapons caches by 2014, but hiccups are likely along the way, said Aaron David Miller, a vice president at the Woodrow Wilson Center and former adviser to several secretaries of state.
"There are bound to be ups and downs, there are bound to be negotiations," Miller said. "What happens when the nickel and diming begins? What happens when you see what's going to be a significant amount of obstruction?"
Under the terms of the U.S.-Russian agreement, Syria could be referred to the U.N Security Council if it does not identify its weapons and give inspectors access, Kerry said. The deal does not include anything on the potential use of military force, Lavrov said, an option the Obama administration had pushed strongly in recent weeks.
"It is very hard to predict where we're going to be two, three, four months down the road with this plan," Kimball said. "What we have is a very clear framework and a very clear schedule for what needs to happen. A great deal of uncertainty has been removed, and that is a major improvement for all parties involved."
An estimated 100,000 people have died in Syria's ongoing civil war, and the continuing conflict is likely to make an already difficult job for inspectors even more complicated, Kimball said.
"It's unprecedented. There are other instances in the past where the country has agreed to eliminate its chemical weapons stockpiles through U.N. Security Council mandates, an example being Iraq in 1991 following the first Gulf War," Kimball said. "There's another situation in 2003, 2004 when Libya renounced its WMD stockpile and inspectors moved in. But neither of these were during wartime or under the threat of further military actions, so this is unprecedented in a number of ways."
One of the most unpredictable factors in the equation is Assad himself, the experts said, and how willing he will be to smooth the road for inspectors and grant access to his government's chemical weapons sites.
"These chemical weapons are among Assad's most important military assets. They know where they are and they're very organized in controlling the chemical agents," Kimball said. "The chemical weapons stockpiles that the Assad regime has are very likely in the best-controlled areas for the government, but still inspectors are going to have to get to those places and obtain access to those places that are going to be behind several layers of security in some cases."
If there's one person sitting at the negotiating table who has seen a similar scenario play out before, it's Lavrov, said John B. Bellinger III, who as a National Security Council legal adviser watched the Russian politician during negotiations around U.N. Security Council Resolution 1441, which in 2002 demanded that Iraq yield up any weapons of mass destruction.
"Lavrov himself is renowned as a very tough negotiator and literally has been through exactly this exercise with 1441," Bellinger said.
The successful removal or destruction of Syria's entire chemical weapons hoard would be a major milestone, if all does go according to plan, Miller said.
"Getting rid of the third-largest stockpile in the world, first largest in the Middle East … would be an extraordinary accomplishment," Miller said.
NBC News' Erin McClam and Jason Cumming, Reuters and The Associated Press contributed to this report.