[Serious] Is a limited nuclear exchange possible?

[Anomalocaris]

I think limited nuclear exchange is unlikely unless the side which initiates it believe it gets ahead by attacking on limited scale even if the enemy successfully retaliates in kind.    Why else would you try?

Conversely any response to the initiation of limited nuclear attack by the other side must escalate to some degree so the other side doesn’t emerge in a better position even after absorbing your response.

So I think initiation of limited nuclear exchange is unlikely.   

I think the threshold for unlimited escalation occurs if the US believe it sees signs of imminent Russian nuclear use and then decide the it has a good enough chance of success with a preemptive attack on Russian nukes to actually try.   If such a effort does not succeed and Russia detects the attack in time to do something about it, then I believe they will launch an all out counter attack in response and a full scale nuclear exchange will result.