I don't know where you read that.
I only said that he is cornered, and a cornered animal is not predictable.
I don't think he would do a first strike as Russia would be destroyed, most of the US's urban centers are already destroyed - Detroit, Oakland, Newark, Philadelphia... our own fifth column took care of many of their potential targets.
The problem is, humanity has a habit for sliding into war... remember FDR - "NO FOREIGN WARS" and a few years later American boys were dying on foreign battlefields.
We don't need a first strike, just a single miscalculation.
An Archduke Ferdinand Moment, a Gulf of Tonkin... a spark and the rest goes on autopilot.
Some people do think Putin is mad enough to try it - some credible people: If Putin goes nuclear
Putin's nuclear option
I cannot find the original article where I read the quote of Obama stating that he would not respond to a nuclear attack in kind. I redact it.
Make up your mind, is he or isn’t he going nuke, say no/yes/no/yes, and how would he get cornered since he is the one doing the invading, and what “spark” can force NATO to defend itself, except a Russian invasion?
Just tell your man to quit invading people and no one will have to defend themselves from him.