It also stated that more than 98 percent of the attacks were carried out by forces aligned with the Assad regime, including the Tiger Forces, whose members were trained and equipped by the Russians. The rest of the chemical attacks were attributed to the Islamic State; only one chemical attack was attributed to the rebel forces.

The GPPI began tracking the use of chemical weapons in Syria in 2012.

According to the report, most of the chemical attacks took place after former US President Barack Obama declared that the use of chemical weapons by the Syrian government comprised a “red line” for the US administration.

GPPI staff said they based the report on testimony by local residents and on field surgeries conducted by doctors in Syria, both at government and rebel-run hospitals. Researchers also made use of chemical analysis of the scenes of some of the attacks, obtained by foreign observers.

“The Assad regime did not merely ‘get away’ with its use of these banned weapons, but succeeded in using them for strategic ends,” the report stated.