The White House has called on Syria to intensify their efforts to remove chemical weapons from the country so they can be destroyed.
Defence Secretary Chuck Hagel said the US is "concerned" that Syria is behind in removing chemical weapons material that are due to be destroyed under an international agreement.
Hagel said he had asked Russian officials to urge the Syrian regime to comply with the deal.
Despite the delay, Hagel believes the removal effort could get back on track.
More top news
Another bitterly cold day after a freezing, frosty morning, not much change this afternoon
Nazanin Zaghari-Ratcliffe's five-year jail sentence is confirmed despite her husband's campaign to bring her home.
A man who was filmed swallowing a goldfish for a drinking challenge is facing jail.