While chemical weapons stocks are relatively secure within army bases and research facilities, there is a greater risk once they are moved that they might fall into the wrong hands -- such as the jihadist groups active among Syria's rebels. However, Syria's chemical weapons are binary weapons, meaning that they are stored as separate ingredients that would have to be combined before becoming lethal. Using them would not be easy for militia groups.
What sort of time limit is feasible for such an operation, and who decides whether the Syrian regime is cooperating fully?
These are huge unanswered questions. The UNSCOM inspectors had to challenge Iraqi officials repeatedly with detailed documentary evidence that not all Iraq's chemical weapons had been declared. There were countless reports to the U.N. Security Council and 12 UNSC resolutions between 1991 and 1996 in support of its work.
Karmon estimates that the whole process in Syria could take three to four years and argues it would be impossible without a cease-fire, with the two sides retreating to allow inspectors to do their work. Given the stakes on the battlefield that Syria has become, that seems unlikely.
What's to stop the Assad regime starting over, especially if it sees a tactical advantage in using such weapons?
In 1989, then-CIA Director William Webster said Syria had begun producing chemical agents in the early 1980s. So Syria has some 30 years of experience in making chemical weapons and has built a network of suppliers all over the world. Defecting military officers have said that Iranian experts have helped develop Syria develop its arsenal and the missiles to deliver chemical weapons (despite Iran itself being targeted by chemical weapons during its war with Iraq.)
Starting a new chemical weapons program would not be technically difficult and could be done discreetly if on a limited scale. It might also be tempting for a regime whose conventional military strength is being eroded. Military analysts point out that Syria began developing chemical weapons capability decades ago to counter Israel's conventional military superiority. That superiority is even greater today than it was, and the Assad regime may one day again see possession of chemical weapons as critical to its survival.