Heightened terrorism risk
The increased focus on Syria’s stockpile is driven in part by the government’s de facto retreat from large portions of the countryside as forces loyal to President Bashar al-Assad concentrate on driving rebels from Damascus, Aleppo and other key cities. Despite setbacks, the opposition Free Syrian Army says that up to half of the countryside is in rebel hands, a claim that underscores concerns that weapons depots could be abandoned or overrun.
U.S. and Israeli officials fear that the chemical sites could be looted, leading to weapons being sold or given to radical Islamists or to Iranian-backed Hezbollah fighters. A single crate of artillery shells or a few barrels of chemical precursors would contain enough lethal poisons for a series of terrorist attacks, weapons experts say.
Mitigating the risk somewhat is the fact that the most of Syria’s stockpile consists of chemical precursors that must be combined and loaded into shells or bombs. Amateurs who attempt to mix ingredients for sarin gas run a strong risk of killing themselves instead of their intended targets.
Still, the terrorism risk has prompted extensive contingency planning by the United States and regional allies, including Israel, Jordan and Turkey, said the U.S. and Middle Eastern officials.
Under the most optimistic scenario, teams of experts could be dispatched into rebel-controlled parts of Syria to secure and remove chemical weapons, as happened in Libya after the fall of Moammar Gaddafi. But if weapons sites are overrun during fighting — or if loyalist forces are seen preparing for a chemical attack — plans call for sending elite foreign military forces to secure the arms under fire, if necessary, according to the officials.
Fears of chemical attacks
Syrian rebels also have grown increasingly concerned about the stockpile, fearful not only about looting, but also about the possibility that Assad will use the weapons against rebel fighters and civilians as a last resort, said Andrew Tabler, an expert on Syria who recently returned from a month-long trip to the region.
“They recognize it as a problem,” said Tabler, author of “In the Lion’s Den,” a book about Syria under Assad. “They think the regime is moving the weapons around, mostly to the coast and other areas where the regime will go if it is forced to contract.”
The Obama administration shares the rebels’ concern that a desperate Assad might decide to use chemical weapons against his countrymen. But despite reports that Syria has consolidated some of its chemical stockpile in recent weeks, intelligence agencies have not detected evidence that Syrian forces are filling chemical shells or otherwise preparing for a chemical attack.