The agreement [between Putin and Erdoğan] also thwarted an alleged plan to stage a chemical attack and lay the blame for it at the door of the Syrian government.
A video has been produced by the White Helmets civil defence group showing “three versions” of a staged attack.
No evidence given. Another round of disinformation about the White Helmets preparing a staged chemical attack in Syria started spreading on August 25 by the Russian Ministry of Defence; see latest cases on White Helmets: https://euvsdisinfo.eu/disinformation-cases/?text=white+helmets&disinfo_issue=&date=
Russia, backing President Bashar al-Assad in Syria, has been preparing for an offensive on the city of Idlib. After Putin’s talks with Turkish President Tayyip Erdogan, Russian Defence Minister Sergei Shoigu told reporters there would not be an offensive now. https://www.reuters.com/article/us-mideast-crisis-putin-erdogan-hope/russia-and-turkey-agree-to-create-buffer-zone-in-syrias-idlib-idUSKCN1LX1BU
According to Bellingcat, “it is clear that Russia and its allies are intent on muddling the media landscape in the event that Assad yet again uses chemical weapons during a future Idlib offensive.” https://www.telegraph.co.uk/news/2018/09/02/russian-disinformation-campaign-syria-threatened-spark-new-war/
On 7 April 2018, a high number of civilians were killed in the besieged Syrian city of Douma, with evidence pointing towards another chemical attack by the regime, according to the EU.
According to the World Health Organisation, during the shelling of Douma on Saturday, an estimated 500 patients presented to health facilities exhibiting signs and symptoms consistent with exposure to toxic chemicals. http://www.who.int/mediacentre/news/statements/2018/chemical-attacks-syria/en/
See also Bellingcat's open source survey on the suspected chemical attack: https://www.bellingcat.com/news/mena/2018/04/11/open-source-survey-alleged-chemical-attacks-douma-7th-april-2018/
In September 2017, the UN Commission of Inquiry on the Syrian Arab Republic summarized 33 separate incidents where it had found use of chemical weapons. Since then there have been several additional suspected chemical attacks. Between March 2013 and March 2017, the Commission documented 25 incidents of chemical weapons use in the Syrian Arab Republic, of which 20 were proven to have been perpetrated by government forces and used primarily against civilians.