The operation is being carried out in line with global law; past U.N. Security Council resolutions; the right to self-defense as enshrined in the U.N. charter; and respect for Syria's territorial integrity.
The Joint Investigative Mechanism (JIM) found Syrian government forces were behind three chlorine gas attacks in 2014 and 2015.
Radi Saad, from the chemical weapons team of the White Helmets civil defense group that operates in rebel-held parts of Syria, told Reuters three of the nine people who suffered from "suffocation injuries" were rescuers responding to the incident.
So far an estimated 134 Free Syrian Army fighters, 106 YPG fighters, and 68 civilians have been killed as a result from the current conflict between the SDF and Turkish military forces in northern Syria.
Regime bombardment killed almost 30 people in a rebel enclave near Damascus on Monday, as Syria's seven-year conflict left civilians paying a heavy price.
The U.S. and Russian Federation clashed yesterday at the United Nations Security Council, after United States Ambassador to the UN Nikki Haley told the council that there was "obvious evidence from dozens of victims" that chlorine had been used in Eastern Ghouta.
Eastern Ghouta, which houses around 400,000 residents has remained under a crippling regime siege for the last five years, the Anadolu news agency reported.
Regime or allied forces have fired suspected chlorine-filled munitions on targets in Eastern Ghouta on several occasions in recent weeks, sparking USA warnings of military action.
In August 2013, hundreds of people are killed in the suburbs of Damascus in chemical weapons strikes after Syrian troops launch an offensive there.
A third accusation of toxic gas use came from Idlib, an opposition-controlled province in the country's northwest that also falls in a de-escalation zone.
US Ambassador Nikki Haley told the council there was "obvious evidence from dozens of victims" to corroborate the chlorine attacks in Eastern Ghouta.
Tuesday's deaths included 14 children and 20 women, SOHR said.
The Idlib area is home to more than 1.1 million of Syria's 6.5 million internally displaced people, many of whom escaped other formerly opposition-held areas after they were overrun by government forces, according to United Nations figures.