Updated at 12:27 p.m. ET
A fact-finding team from the Organization for the Prohibition of Chemical Weapons is now on its way to Syria and will begin working there by Saturday, OPCW spokesperson Johan de Wittlaan said on Thursday.
The team will investigate the recent killing of dozens of civilians in Douma, scene of a horrifying attack over the weekend, in which Syrians were found to have died from suffocation in the city that's just outside Damascus.
"I think it looks pretty clear that a chlorine weapon was used" on the civilians, said Charles Duelfer, former deputy head of the U.N. inspections team in Iraq, in an interview with NPR.
When asked about expectations that the U.S. will launch a punitive strike on Syria over the attack, U.S. Secretary of Defense Jim Mattis said, "Some things are simply inexcusable — beyond the pale — and in the worst interests of not just the chemical weapons convention, but of civilization itself."
Syria and its main ally, Russia, have denied any chemical weapons were used and gave permission for the OPCW to investigate.
Confirmation of the fact-finding team's trip comes after Russia said that Douma had finally come under the government's total control, after the last rebel group that had been fighting Syria's regime there capitulated. As part of the takeover, Russia said, it will deploy military police in the city — a development that could lead to questions about the validity of the evidence at the scene.
The U.S. and other nations have condemned Syria's apparent use of a poisonous gas to attack Douma's civilians, particularly as it occurred in an area that was supposed to have been off-limits to warplanes. Since the attack, President Trump has been engaged in a spat with Russia — which threatened to shoot down any U.S. missiles that might be launched against Syria in retaliation.
Trump said on Wednesday that the U.S. will strike Syria using missiles that are "nice and new and 'smart!'" — ramping up expectations that an attack was imminent. But on Thursday, he tweeted, "Never said when an attack on Syria would take place. Could be very soon or not so soon at all!"
As Trump has talked about ordering a new military strike on Syria, the regime led by President Bashar Assad has been busy. From Beirut, NPR's Ruth Sherlock reports on preparations for a U.S. attack:
"They're thought to be moving planes and weapons to more secure locations. They've apparently evacuated a lot of the main airports and military bases. Air defenses are on high alert. And for the civilian population, there's this kind of palpable sense of fear.
"People in the capital Damascus were saying that they have been up into the early hours of each night waiting for a possible attack. And one person said, 'You can cut the tension with a knife here.' "
Douma is just six miles northeast from the center of Damascus. It's been fought over since at least 2012, when government troops battled for control of both the city and the broader Eastern Ghouta region. Since that time, much of the rebel enclave has been under siege.
The recent attack on Douma came after months of warnings that the "de-escalation zone" status of Eastern Ghouta had become "a farce," as State Department spokesperson Heather Nauert said in February, when the U.S. accused Russia and Syria of carrying out attacks on civilians, targeting medical facilities, and using siege tactics.
Thousands of people have fled Douma and Eastern Ghouta, desperate to find safety. In the last 12 days alone, 12,000 people left the city, Syria's state news agency said. Across Eastern Ghouta, more than 165,000 people have left via secure corridors. Rebel groups made deals to secure their safety as they departed — many of them heading north for Idlib. Then came the news that the last holdout group, Jaysh al-Islam, had finally agreed to leave. Many of them also reportedly headed north, to Aleppo.
"Today marked a landmark event in Syria's history," said Yuri Yevtushenko, who heads the Russian Center for Reconciliation of the Opposing Parties in Syria. As reported by the state-run Tass news agency, Yevtushenko added that Syria's official flag had now been hoisted over Douma, signaling control over Eastern Ghouta.