U.S. Secretary of State Mike Pompeo has accused Syria of using chlorine gas in an attack against rebels in the northwest of the country in violation of conventions prohibiting the use of chemical weapons.
Pompeo said on September 26 that the strike took place on May 19 in Latakia Province.
"The United States will continue to pressure the insidious Assad regime to end the violence directed against Syrian civilians," Pompeo said, referring to Syrian President Bashar al-Assad.
Pompeo said the Syrian government has used chemical weapons every year since 2013, when Damascus joined the international convention against their use.
The U.S. special envoy for Syria, James Jeffrey, said the United States knows that "a number" of people were injured in the attack but that it does not appear that anyone was killed during the attack.
Western experts have also blamed Syria for several chemical weapons attacks in recent years. Damascus, backed by Russia, has denied it was involved in any such attacks and has blamed rebel fighters instead.
In March, the Hague-based Organization for the Prohibition of Chemical Weapons (OPCW) determined that chlorine was used against the rebel-held Syrian town of Douma in 2018, in a long-awaited final report on the attack that killed 43 people.
The mission's mandate does not include laying blame, but Western powers led by the United States said Assad’s government was responsible for the attack and launched air strikes on Syrian military installations in response.