The White House says Syria must intensify its efforts to transport chemical weapons to the port of Latakia, after a news report showed work to deliver and destroy the weapons had fallen behind schedule.
White House spokesman Jay Carney says "it is the Assad regime's responsibility to transport those chemicals" safely.
Reuters cited sources on Wednesday saying Syria has given up less than five percent of its chemical weapons arsenal and will miss its deadline next week to send all toxic agents abroad for destruction.
The sources also told Reuters the internationally backed operation to remove the weapons is six to eight weeks behind schedule.
Meanwhile, Defense Secretary Chuck Hagel reiterated U.S. "concern" about getting Syria's chemical weapons out of the country. He said he and does not know whether it is Syrian incompetence or a delay tactic on the part of President Bashar al-Assad's government.