Ukraine: What are chemical weapons and could Russia use them?

All of these so-called chemical agents can be used in warfare in artillery shells, bombs and missiles. But all are strictly prohibited by the Chemical Weapons Convention of 1997, signed by the vast majority of nations, including Russia. The global watchdog for chemical weapons is in the Hague, Netherlands, and is called the OPCW – the Organisation for the Prohibition of Chemical Weapons – which monitors the unlawful use of these weapons and tries to prevent their proliferation.