What happens to Bashar al-Assad's stockpile -- one of the largest in the world -- if the deeply divided and untrained rebels overthrow his regime?

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An undated photo provided by state media shows Syrian army tanks firing. (AP)

It looks like a perfect storm. Syria is believed to harbor one of the world's largest stockpiles of chemical weapons--which, for the time being, appear to be protected by well-trained Syrian troops. As violence in the country rages, however, Washington and its allies are eager for Syrian President Bashar al-Assad to leave power.

With Syrian opposition groups claiming that up to 17,000 people have died in the conflict, this sentence is an uncomfortable one: Assad's strong hold on power has so far, from a chemical-weapons standpoint, staved off a potential disaster without an easy fix. The U.S. cannot rely on the deeply divided and untrained Syrian rebels to control the stockpiles; there's little appetite in Washington for military intervention to secure them; and al-Qaida is in a country that also has long-standing ties to Hezbollah in Lebanon. All this means that Syria is virtually sure to become the next major proliferation challenge in the region for years to come.

The Obama administration and the Pentagon are keeping possible contingency plans for Syria's chemical weapons under close wraps, saying publicly only that they are closely monitoring the situation. But things just got more complicated: As The Wall Street Journal reported on Friday, Syria has begun moving some of its massive chemical stockpiles out of storage facilities, sparking fears that Assad may consider deploying them against civilians or enemies. The U.S. still believes the weapons are under Assad's control--and some officials believe he may be trying to safeguard the material--but the latest development underscores what some worry is a fundamental lack of preparation in Washington for what might happen next.

"I am convinced that the administration needs to be much more aggressive in its contingency planning regarding chemical weapons from an operational standpoint," House Intelligence Committee Chairman Mike Rogers, R-Mich., said. "You have to go into this thinking, 'What if [Assad falls] tomorrow? Are we ready?' I can't talk about operational details. But I don't believe that we're ready. If the regime were to fall this week, I think we'd be in serious trouble."

Despite calls for a speedy transition in Syria, the nightmare scenario for chemical weapons would be the sudden collapse of Assad's power-- or for the security situation to quickly devolve as he gets desperate. The trained custodians of the chemical-warfare facilities scattered across the country could be called to fight more-pressing battles and abandon their posts. Or they might defect and sell the materials to the highest bidder, potentially to Hamas and Hezbollah. Potential wholesale looting means nonrational actors like al-Qaida, which Rogers affirmed already has a "significant" presence in the country, are more likely to obtain the weapons and try to use them in plots to strike Western targets.

Syria, one of the few countries that never signed the 1992 Chemical Weapons Convention, is believed to have, among other things, mustard gas, a sarin nerve agent, and even VX. Analysts and officials also believe Syria has ballistic missiles that can be fitted with chemical warheads, and tens of thousands of shoulder-fired missiles that terrorists could use to target civilian aircraft.

In February, CNN cited a military planning estimate that 75,000 ground troops would be needed to secure Syria's chemical-weapons storage and production sites scattered throughout the country. The White House does not appear inclined to support such an intervention. Officials have publicly warned about the risks posed by Syria's sophisticated Russian-made air defenses. Any full-scale military operation is virtually certain to be long and difficult, with heavy risk of both coalition and civilian casualties. There's no guarantee troops would solve the problem--or that an international consensus could be reached to deploy them, especially with the not-so-distant memory of flawed intelligence about Saddam Hussein's weapons of mass destruction in Iraq. Even there, 200,000 U.S. and coalition troops were unable to secure documented sites of sophisticated explosives, which were looted and used in IEDs.

An air campaign alone would be unlikely to solve the challenge. While the U.S. can destroy deeply buried targets, Charles Blair--senior fellow for state and non-state threats at Federation of American Scientists--said that "no country has the burrowing capability, even with nuclear weapons, to destroy very deep targets without creating an enormous radioactive fallout cloud." Even strikes on targets above ground would risk spreading the agent. These strikes, Blair said, would cause an "unacceptably high number of agents still in existence and still available."

Leonard Spector, deputy director of the Monterey Institute of International Studies' James Martin Center for Nonproliferation Studies, outlined a smaller-scale military option. Surveillance assets might observe an empty truck convoy approaching one of the chemical sites, Spector said. A targeted operation with drone strikes or even special-forces troops could disrupt this activity.

The U.S. could also train its Arab League partners to secure the sites if more widespread devolution occurs. Spector said that June's Eager Lion 12 exercise in Jordan brought together 19 nations to work on various contingencies, including the possibility that chemical weapons could be taken across Syria's borders.

However, if agents are already walking away, it's too late for the best possible outcome, Blair said. As rebels (or terrorists) try to figure out how to use or even transport the different agents, there could be potentially significant casualties, Blair said. Fear alone of loose chemical weapons could spark widespread panic and devastate the global economy.

In the meantime, Spector argues the U.S. should encourage the sites' trained custodians--who may be contemplating defection--to remain in place. "You want to advise them that if they stick to their mission of protecting these sites ... that they will be treated in a special category that will get some protection," Spector said, calling on Washington to advise the Syrian opposition to get this message out. However, Syria's opposition is still disorganized, and the West retains a lingering distrust of opposition groups with possible extremist ties.

The recent past offers some tough lessons. Libya's arsenal pales in comparison to Syria's sophisticated conventional weapons systems, but the U.S. allocated some $40 million for American and European specialists to clear the roughly 20,000 surface-to-air missiles and other weapons believed to be within that country. But the Libya mission launched after the violence and NATO bombing campaign left sites open to looting. The U.S. still cannot account for all the weapons thought to be missing. Loose weapons from Libya are believed to be partly responsible for rising violence in nearby Mali, where the democratically elected president was overthrown in a March coup.

Best-case scenarios for Syria's chemical weapons appear to be pipe dreams: Assad is highly unlikely to willingly leave power willingly and allow a negotiated transition; and his downfall isn't likely to come from a clean overthrow by the rebels, either. Assad's hold on power inadvertently prevents the need for a rapid response to contain the massive stockpile chemical weapons--but Washington must develop a long-term plan if its policy is truly for the strongman to leave power.

There is one outcome that could demand international action before that day comes: if Assad deploys chemical weapons against his own people. "The humanitarian consequences would be so grave, and the international outrage so severe, that could lead to a much more substantial intervention," Spector said. Even Assad's strongest ally, Russia, would be hard-pressed to argue against it. "That is an unspoken red line."

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