UN Probe Finds Assad Regime Used Chemical Weapons in Attacks on Syrians

The White House is condemning Syrian President Bashar al-Assad's regime for using chemical weapons against Syrians, after the United Nations and the Organization for the Prohibition of Chemical Weapons confirmed suspicion of chemical weapons use in Syria in 2014 and 2015.

Three years to the week since President Obama pulled back from striking Syria over its use of chemical weapons, the investigation found that the Syrian government was responsible for two chlorine gas attacks in April 2014 and September 2015 in Idlib in the north of the country.

"It is now impossible to deny that the Syrian regime has repeatedly used industrial chlorine as a weapon against its own people in violation of the Chemical Weapons Convention and U.N. Security Council Resolution 2118," White House National Security Council spokesman Ned Price wrote in a statement Wednesday. "We condemn in the strongest possible terms the Asad regime's use of chlorine against its own people."

The inquiry -- unanimously authorized by the U.N. Security Council -- would be the first time a perpetrator has been identified. The results are due to be discussed by the Security Council next week, after which the report will be made public.

The investigation was set up with the threat of imposing Chapter 7 sanctions against those responsible -- the part of the U.N. charter that deals with sanctions and authorization of military force. However, the U.N. Security Council would need a further vote to impose sanctions -- setting the stage for a fight with Russia and China, who may veto any future sanctions against the Syrian government.

Chlorine's use as a weapon is prohibited under the 1997 Chemical Weapons Convention, which Syria joined in 2013. In 2013, the Syrian regime agreed to remove and destroy its chemical weapons.

"The OPCW-UN report also confirmed that in August 2015, ISIL used mustard gas against civilians in Syria," Price noted. "The U.S.-led Counter-ISIL coalition has placed a high priority on targeting ISIL's chemical weapons capabilities, including by capturing one of its chemical weapons manufacturing leaders in March 2016 and using information gained from him to launch airstrikes to degrade ISIL's ability to use such weapons. We continue to remove leaders from the battlefield with knowledge of these weapons and will target any related materials and attempts to manufacture such chemicals going forward."

Asked about these reports that Assad didn't turn over all the materials involved in chemical weapons production in Syria, Earnest reiterated the achievements years ago when Assad turned over and destroyed chemical weapons.

"What we were able to achieve a couple of years ago in getting the Assad regime to acknowledge that they had a significant quantity of chemical weapons, rounding up those chemicals and destroying them, made the world safer. It eliminated a significant proliferation risk," he said. "We have a country that is overrun by extremists. Having large quantities of chemical weapons floating around is not a good idea and not a good combination. So we've been pleased that the Assad regime's declared chemical weapons stockpile was rounded up and destroyed, but the situation in Syria has been murky for quite some time."

"We've also been -- expressed our previous, long running concerns about the gratuitous violence that's used by the Assad regime against innocent civilians, including the weaponization of otherwise common chemicals to try to exacerbate the violence in that country. And I'm referring to chlorine, a commonly available industrial chemical that, according to some reports at least, the Assad regime is using as a weapon," he continued. "And that is something that's a deep concern to the international community and certainly to the United States."

U.S. Ambassador to the United Nations Samantha Power called on the international community to act "to hold accountable those who act in defiance of such fundamental international norms."

"When anyone -- from any government or from any terrorist group -- so flagrantly violates the global ban on chemical weapons use without consequences, it sends the signal that impunity reigns and it gravely weakens the counter-proliferation regime from which all of us benefit," Power stated.

"It is essential that the members of the Security Council come together to ensure consequences for those who have used chemical weapons in Syria. It is essential that all state and non-state actors immediately cease any chemical weapons use. We strongly urge all States to support strong and swift action by the Security Council," she said.

ABC News' Jon Williams contributed to this report