In August 2015, the U.N. Security Council first authorized the OPCW and U.N. investigators to probe reports of chemical weapons use in Syria, as witnesses began to circulate increasing accounts of chlorine attacks by government forces against civilians in opposition-held areas.
"A perfectly executed strike last night", Mr Trump tweeted early Saturday.
Chlorine, in contrast, has been used more widely in Syria's conflict without past USA reprisals, and the chemical itself is far easier to find and weaponise, experts say.
Vice President Mike Pence attends the Eighth Americas Summit in Lima, on April 14, 2018.
US Ambassador to the United Nations Nikki Haley on Sunday warned that a chemical attack could take place in the United States as well, if "we are not smart enough".
The military officials said they were confident that Syrian government installations that produced chlorine gas and sarin, a nerve agent, were destroyed or damaged.
Chlorine, in contrast, has been used more widely in Syria's conflict without past USA reprisals and is far easier to find and weaponise, experts say.
The Trump administration has placed sanctions on Russian individuals and entities, including penalties last month targeting Russian oligarchs who are close to President Vladimir Putin.
Western powers blamed President Bashar al-Assad, but Syria and its ally Russian Federation categorically denied the claims and accused the West of "fabricating" the incident to justify military action.
Allegations of blame: Western allies accused the Russian-backed Syrian regime of being behind the attack.
The US Department of Defense says that a chemical weapons storage facility was targeted, in addition to a chemical weapons equipment storage facility and command post. Russia, which had promised to respond to any attack on its ally, said that Syrian air defences had intercepted 71 of the missiles fired.
However, one of the stated goals of the strikes was to deter Syrian President Bashar Assad's government from using chemical weapons again.
But the military seemed less than troubled as it claimed that Syrian aerial defenses managed to shoot down most of the missiles and divert others.
"Everyone is celebrating and declaring victory which is freakish since so many Syrians have suffered over the years, and the bombings have just taken place", he said. "We put facts contrary to your myths", he said.
The three countries launched their missiles even as the fact-finding team from the Organization for the Prohibition of Chemical Weapons was in the Syrian capital and had been expected to head on Saturday to Douma.
But analysts question the reasons for these latest raids - which signalled that Western leaders would not let a chemical weapons attack go without punishment - but demurred about deeper involvement when barrel bombs are used. "If there were chemical weapons, we would need to wear masks and take other protective measures to be staying here", he said.
Russian Federation filed a draft resolution condemning the missile attack as a violation of worldwide law and the UN Charter, and demanding the United States and its allies cease aggression against Syria.