Sure they are.
Seriously, Putin would probably use tactical nukes before he's use chemical weapons. He'd receive the same level of international condemnation but at least the nukes would be more effective.
He has used them before - Chechen Republic...
“Seriously, Putin would probably use tactical nukes before he’s use chemical weapons. He’d receive the same level of international condemnation but at least the nukes would be more effective.”
And much easier to contain.