Novichok hoax.
https://www.veteranstoday.com/2018/07/04/oh-no-not-another-novichok-farce-surely/
https://www.veteranstoday.com/2018/03/20/russian-nerve-agent-attack-complete-hoax/
"There is no record of the Novichok group of nerve agents having been declared by a state party to the Chemical Weapons Convention,” the Organization for the Prohibition of Chemical Weapons (OPCW) said in a press release on Friday. Nearly all countries in the UN are members to the OPCW, except for Egypt, Israel, North Korea and South Sudan."
https://www.veteranstoday.com/2018/03/17/opcw-no-member-states-known-to-possess-novichok-class-nerve-agents/