Some 30 tons of the most lethal weapons -- including mustard gas and components of sarin and nerve agent VX -- are supposed to be shipped out of Syria by Dec. 31 under a U.N.-backed schedule set by the Organization for the Prohibition of Chemical Weapons based on a U.S.-Russia agreement to dismantle the arsenal.
"In view of the circumstances in this country, it will be quite difficult to meet this timeline," OPCW Director General Ahmet Uzumcu said in Oslo, Norway, where he was to accept the 2013 Nobel Peace Prize on behalf of his organization.
The rest of the weapons stockpile is to be removed by Feb. 5 under the plan.
"This is also quite an ambitious timeline. We don't know if we can meet it," Uzumcu said. "There might be a few days' delay."
A Defense Ministry adviser told Britain's Daily Telegraph there was a grave danger the truck convoy would be attacked on the highway linking Damascus with the port city of Latakia.
"If this area is still contested when the stockpile has to be transported, you have to be very worried about how the Syrians are going to move this material," the adviser said.
"There have already been roadside bombs in the area and we have seen in Iraq and Afghanistan how large and sophisticated these devices can be. If they can blow a tank 3 meter in the air, they can disable trucks and stop the convoy.
"It's also very had to see how the OPCW and the U.N. will be able to supervise the shipment if they are not able to travel into these areas," the adviser said.
The mustard gas and other agents are expected to be packed into 140 shipping containers Syria claims will be bulletproof. They are then expected to be moved in a truck convoy to Latakia.
The mustard and sarin gas is to be ferried from Latakia by a Danish cargo vessel escorted by a Norwegian warship to the U.S. Navy's MV Cape Ray, where it will be destroyed.
The Cape Ray will likely anchor in international waters in a location that hasn't yet been determined, the Wall Street Journal said.
Senate Democrats to pull all-nighter on climate change
Susan Sarandon 'very excited' about daughter's pregnancy