The United States says only about 4 percent of the chemical weapons declared by the Syrian government has been removed and it is concerned the handover was behind schedule.
On a visit to Poland, US Defence Secretary Chuck Hagel told reporters he did not know the reason for the delay but said Damascus "had to take responsibility for fulfilling its commitment".
Syria is believed to possess 1300 tonnes of chemical agents including sarin and the more potent nerve agent VX. The stockpiles are due to be removed and destroyed by 30 June.
Two consignments left the port of Latakia in January, according to the Organisation for the Prohibition of Chemical Weapons (OPCW).
The international watchdog overseeing the destruction of Syria's chemical arsenal is meeting in The Hague to discuss the operation's progress.
Meanwhile, a new report by the group Human Rights Watch says the Syrian government has been "deliberately and unlawfully" demolishing thousands of homes in opposition strongholds.
It said satellite images appear to show large-scale demolitions with explosives and bulldozers in opposition strongholds in Damascus and Hama.
The report said the apparent wanton destruction of civilian property and collective punishment are war crimes.