They absolutely have
They've just been routed in one region, masses of troops are rumoured to be surrendering in another, newly established regiments are refusing to go to Ukraine and are now officially not being sent, Putin has run for the hills (his mansion in Sochi), Russian politicians it its two major cities are openly calling for him to resign, even some of his TV Nutjobs are pretty much saying openly on TV that the situation in Ukraine is fubarred, the troops actually in battle are totally demoralised....
What else needs to happen for him to become desperate?
They stopped threatening nukes ages ago because it was a bluff and that bluff got called