David Jackson

USA TODAY

Aides to President Obama are expressing concern that Syria may still have chemical weapons, and they could fall into the hands of the insurgent group ISIL or other terrorists.

Samantha Power, the U.S. ambassador to the United Nations, told reporters Thursday that there are "discrepancies and omissions" in Syria's declaration that it has scrapped its chemical arsenal pursuant to an agreement that Bashar al-Assad's government made last year.

"We must ensure that the Syrian government destroys its remaining facilities for producing chemical weapons within the mandated time frames and without the repeated delays by the Assad regime that plagued earlier removal efforts," Power told reporters.

Last year, the Obama administration had threatened airstrikes against Syria for using chemical weapons against anti-government protesters, before Assad agreed to forfeit to them.

Now the insurgent group ISIL has taken over swaths of Syria and neighboring Iraq. The Obama administration has authorized air strikes against ISIL in northern Iraq, and is considering possible action against the insurgents in Syria.

"Certainly if there are chemical weapons left in Syria, there will be a risk that those weapons fall into ISIL's hands," Power said. "And we can only imagine what a group like that would do if in possession of such a weapon.

She added that the United Nations Security Council "intends to stay very much on top of this."

From the Associated Press:

"Syria agreed to give up its chemical arsenal last year when President Barack Obama threatened missile strikes in retaliation for a chemical attack on a rebel-held suburb of Damascus, believed to have killed more than 1,000 people. Assad's government had denied involvement in the attack, blaming the rebels.

"The weapons, tons of them, were destroyed aboard the U.S. cargo vessel MV Cape Ray in international waters. ...

"Questions persist over whether Assad is hiding undeclared poison gases and there is an investigation into reports of alleged chlorine gas use in some Syrian towns. Chorine is not specifically classified as a chemical weapon."