The incident reportedly occurred on the morning of May 19, but the US did not provide details.
In a statement release Tuesday by Morgan Ortagus, spokesperson for the US Secretary of State, the administration warned the US and its allies would respond “quickly and appropriately” if chemical weapons are found to have been used.
“Unfortunately, we continue to see signs that the Assad regime may be renewing its use of chemical weapons, including an alleged chlorine attack in northwest Syria on the morning of May 19, 2019,” Ortagus said.
“We are still gathering information on this incident, but we repeat our warning that if the Assad regime uses chemical weapons, the United States and our allies will respond quickly and appropriately.”
The US has twice launched retaliatory strikes on Syrian targets, in 2017 and in 2018, in direct response to the suspected use of chemical weapons on civilians.
Regime ally Russia alleged in recent days that chemical attacks have been staged by rebel factions to discredit the regime and provoke a western response.
Likewise, the US has accused the regime seeking to justify a new offensive on Idlib by pinning responsibility for the attacks on the rebels.
In a statement earlier on Tuesday, the Russian Ministry of Defense accused Syrian rebels of staging “performances of so called use of chemical weapons against the civilian population … under the guidance of US intelligence officers”.
“The terrorists operating in the Idlib de-escalation zone have a significant amount of toxic substances, which the militants equip ammunition for the performances of so called use of chemical weapons against the civilian population by the government troops,” the Russian statement said.
The US State Department hit back, accusing Russia and the regime of a “continuing disinformation campaign”.
“At times, Russia and the Assad regime have made these false allegations as a pretext in advance of the Assad regime’s own barbaric chemical weapons attacks,” Ortagus said.
“The facts, however, are clear: the Assad regime itself has conducted almost all verified chemical weapons attacks that have taken place in Syria,” the statement added.
Damascus is yet to comment on the US statement.
The US has demarcated the use of chemical weapons as a “red line” throughout the long-running conflict in Syria.
Reports of Assad’s use of chemical weapons date back as far as 2011, and include the massive August 2013 sarin gas attack that killed more than 1,400 civilians in the Damascus suburb of Ghouta.
US National Security Adviser John Bolton told reporters in January the Syrian regime should be “under no illusion” that the use of chemical weapons in Syria will be met by “a very strong response, as we’ve done twice before,” referring to the punitive strikes carried out by the US and its allies.
The fresh allegations come as the regime and Russian forces launch a new offensive on the greater Idlib area, where up to three million fighters and civilians are thought to reside.
The province is mostly controlled by Al-Qaeda’s former Syrian affiliate Hayat Tahrir al-Sham (HTS) – a coalition of anti-Assad jihadist groups.
The offensive breaches a ceasefire deal brokered in September 2018 by Russia and rebel ally Turkey, designed to create a buffer zone around Idlib.
