Abu Dhabi -- Defense Secretary Chuck Hagel said the intelligence community believes the Syrian government has used chemical weapons against its people.
The intelligence community, Hagel said, has determined with "varying degrees of confidence" that Syrian President Bashar Assad's forces have used the nerve agent sarin against civilians and forces fighting to remove Assad from power.
Any use of chemical weapons, Hagel said, would violate standards of warfare.
The White House is informing Congress about the chemical weapons use now, Hagel said.
President Obama has said the use of chemical weapons would be a "red line" that could trigger U.S. reaction.
Hagel's comments represents the first U.S. confirmation of alleged Syrian use of chemical weapons. On Tuesday, Hagel said he doubted Syria had used the weapons after an Israeli intelligence officer had said during a security conference in Israel.
Brig. Gen. Itai Brun, the head of research and analysis in Israeli military intelligence, said Tuesday that Syria had used chemical weapons multiple times. "Shrunken pupils, foaming at the mouth and other signs indicate, in our view, that lethal chemical weapons were used," he said.
Brun also said the Syrian regime was using less lethal chemical weapons, and that Russia has continued to arm the Syrian military with weapons such as advanced SA-17 air defense missiles.