On Monday, Syria became formally bound by the international treaty banning chemical arms, according to the Organisation for the Prohibition of Chemical Weapons.
The head of the agency, which trying to rid Syria of its chemical stockpile, said both the government and rebels have been cooperative. But much remains to be destroyed, Ahmet Uzumch, chief of the Organisation for the Prohibition of Chemical Weapons, told CNN's Frederik Pleitgen.
"Their stockpiles are quite substantial," Uzumch said. "We have about over 20 sites to be visited by the end of this month at least once."
Production facilities have to be deemed ineffective by the end of the month, too.
The rest of the weapons have to be inventoried. Once the inventory is complete, they will be destroyed, Uzumch said.
But the weapons won't be destroyed where they are stored; they'll have to be moved to a safer place, in some cases to other countries.
On the global scale, Uzumch said the OPCW is pretty close to eradicating chemical weapons worldwide. He said it will take four to five years to destroy the stockpiles they know about.
But six countries have yet to join sign on to the Chemical Weapons Convention, so it's not clear what their possible stockpiles might look like.