If history is any measure, the clock is ticking on Assad to disarm

Experts say speed is of the essence.

“You have a very limited time to do as much as you can with maximum political support,” said David A. Kay, who led major efforts in the 1990s to find and destroy Iraq’s unconventional arms. “The political support will start to erode. The people you’re inspecting will get tired. So you want to do as much as you can, as quickly as you can.”

But the destruction of chemical agents is a painstaking process that, to be done safely and securely, can easily take decades. And even the preliminary steps are laden with potential political hurdles and environmental risks, and possibilities for obfuscation and deception.

“We don’t want to create another chemical weapons disaster; Syria has already had several,” said one senior administration official who has knowledge of the meetings over how to separate Mr. Assad from the arsenal that he and his father have built up over the past three decades. He insisted on anonymity because he was discussing internal deliberations. But if Mr. Assad does not put on “a big, demonstrable show” to prove to the Syrian military that he is “giving up the crown jewels,” the official said, “this isn’t going to work.”