Recurring pro-Kremlin narratives aiming to discredit the White Helmets and claiming that the Khan Shaykhun and Douma chemical attacks were staged by Western actors in order to justify military action against the Assad regime.
The OPCW’s Fact Finding Mission confirmed that people in Khan Shaykhun were exposed to sarin, a chemical weapon, on 4 April 2017. "The OPCW FFM has confirmed the use of sarin, a nerve agent, during the 4 April incident in Khan Shaykhun in Syria,” mentioned its Director-General in a report published on June 30, 2017.
The UN-OPCW Joint Investigative Mechanism found Syria’s Government responsible for the attack in Khan Shaykhun. On April 2018, Russia vetoed a US-drafted UN Security Council resolution that would have created a new inquiry to ascertain responsibility for chemical weapons attacks in Syria. In June, the OPCW members granted it power to assign responsibility for chemical attacks.
The United Nations Human Rights Council stated that the Syrian government forces are responsible for the attack. “Government forces continued to deliberately target civilians, including through the use of chemical weapons against civilians in opposition-held areas. As part of an aerial campaign in northern Hama and southern Idlib, on 4 April the Syrian air force used sarin in Khan Sheikhoun, killing over 80 people, most of whom were women and children,” says the report. Syrian government forces and their ally Russia continue to deny these facts.
See Bellingcat Investigation Team's article on Chemical Weapons and Absurdity: The Disinformation Campaign Against the White Helmets.
More information is available here.