Top US officials voiced concern that a deadline set with Damascus to remove the most dangerous chemical arms from the country had been missed by a month.
"Syria must immediately take... The necessary actions to comply with its obligations," said State Department spokeswoman Jen Psaki.
"This is not rocket science here. They're dragging their feet. We need them to pick up those feet and run with this and move forward in moving the chemical weapons stockpile to the ports."
Defence Secretary Chuck Hagel and the White House also voiced concern over the delay and pressed Damascus to solve the problem.
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Just two shipments of around 16 metric tonnes each of so-called Category 1 chemicals have left Syria's port of Latakia this month as part of an internationally backed disarmament plan supervised by the UN and the Organisation for the Prohibition of Chemical Weapons (OPCW).
Hagel said he raised the issue with Russian Defence Minister Sergei Shoigu on Wednesday, asking him "to do what he could to influence the Syrian government."
Psaki also took issue with reported Syrian comments that they did not have the equipment and resources necessary to move the stockpile to the port.
"That is false," she said, adding "we all know that the Syrian regime has the capability to move these weapons since they have been moved multiple times during the conflict."
"It is the Assad regime's responsibility to transport those chemicals safely to facilitate their removal," said White House spokesman Jay Carney.
"We expect them to meet their obligations to do so."
The UN Security Council backed a US-Russian deal last year to eliminate Syria's vast chemical arsenal.