Yeah, painting Putin to a losing corner will just mean possible more destruction including nukes, he must have a face-saving out, because kicking him and expecting him to retreat with his tail between his legs before he's exhausted all options is unrealistic. IMO that's why NATO doesn't want to get involved (yet), the USA can bomb Putin's forces out of Ukraine, but it'd be too embarrassing for Putin to accept without a fight, and for that fight he still has... nukes.