It is justification for their next escalation. They are basically claiming the use of Weapons of Mass Destruction at this point. Notice how that term has fallen out of favor as of late? It is only used when media/government wants to associate easier to obtain bio and chemical weapons in with nukes.
It doesn’t actually have to be all that credible either, all they need to do is convince their own people. Many if not most of them will want to believe it.
I give it no more than 48 hours before Sean Hannity has some Deep State shill on his TV show, and he stops his own bloviating just long enough for this guest to reveal that these chemical and biological weapons were planted in Ukraine by the Russians after they were removed from Iraq in 2003.