Of course, but there's a very real possibility that every action and choice we make at this point leads to the same outcome, just via different routes. If Putin uses a WMD of any kind, and we respond, it will likely lead to a nuclear response. If he uses a WMD of any kind and we do not respond, it'll likely lead to a nuclear event, either from Putin himself, or from an eventual future invasion by Putin on a NATO country... which will demand a response, which will go nuclear.
So, what sequence of events do you see playing out that don't involve someone physically close to Putin just shooting him that will not lead to a nuclear event?