Inspectors from an international watchdog reportedly discovered traces of deadly nerve agents at a military research site in Syria, potentially bolstering evidence that contradicts President Bashar al-Assad's denials that the country still possesses and is using chemical weapons during its ongoing civil war.
Inspectors from the Organization for the Prohibition of Chemical Weapons (OPCW) found chemical precursors used to make the nerve agents sarin and VX in samples taken from Syria's Scientific Studies and Research Centre in December and January, anonymous diplomatic sources told Reuters on Friday.
Despite agreeing to a deal brokered by the US and Russia in 2013 to destroy his country's chemical weapons program, Assad has repeatedly been accused of using chemical weapons.
Related: Syrian President Bashar al-Assad Denies Chemical Weapons Use in French TV Interview
The US almost intervened in Syria in 2013 after reports emerged that Assad dropped sarin gas on the Damascus suburb of Ghouta, killing some 1,400 people. To avoid intervention, Assad turned over 1,300 tons of chemical weapons to the UN and OPCW for destruction.
Assad also agreed to join the Chemical Weapons Convention, which forbids the use, manufacture, or stockpiling of chemical weapons as a tool of war. But the most recent findings by the OPCW seemingly indicate that Assad did not destroy all of his weapons.
"This is a pretty strong indication they have been lying about what they did with sarin," a diplomatic source told Reuters. "They have so far been unable to give a satisfactory explanation about this finding."
The OPCW, which oversees the Chemical Weapons Convention, began carrying out an investigation into the use of chlorine as a chemical weapon by the regime in April 2014 after reports emergedthat the gas was being used in attacks. The Syrian government has blocked the fact-finding mission from accessing the sites in northern Syria where there was suspected use of chlorine on villages. The commission said that chlorine has been used "systematically and repeatedly," but is not authorized to specifically name those who use it.
On Friday, three American diplomats separately accused the Syrian regime of using chlorine as a chemical weapon.
Related: Horrifying Videos Shown at UN Display Carnage of Suspected Chlorine Attacks in Syria
The American ambassador to the OPCW, Robert Mikulak, said there is a "steady stream" of credible reports that the Assad government is using chlorine as a chemical weapon. Deputy Secretary of State Antony Blinken also said he believes the reports.
Samantha Power, US Ambassador to the United Nations, also agreed that Assad has been dropping chlorine-filled barrel bombs on neighborhoods to kill his own citizens, according to the Wall Street Journal.
"As you know, only the regime has helicopters," Ms. Power said. "So we believe the factual record is quite straightforward and devastating in terms of Syrian regime use."
The regime denies they used chemical weapons in 2013, and has said opposition groups were responsible for the attacks in Ghouta, although they offered no evidence to support those claims.
The chemical weapons that the Assad regime is accused of using are considered some of the deadliest by the OPCW. Chlorine is a choking agent, while sarin and VX are categorized as nerve agents. All of them can cause death and severe suffering.
Chemical weapons were first used in World War I and caused massive devastation, leading many countries to ban them. The attacks in Ghouta were the first time a government has used chemical weapons since Saddam Hussein targeted Iraq's Kurdish population in 1988, according to Human Rights Watch.
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