The reasoning is that retaliating is US doctrine—they generally respond to hostile actions in-kind, to deter them. If Ukraine got nuked, the level of outrage would place intense pressure on Biden to do something, and the hawks would become a lot louder than the doves, similar to after the 9/11 attacks. In the case of Russia, the US has exhausted most non-military avenues already. And US is a very militaristic country—they have many times bombed countries (Syria, Iraq, Afghanistan, Libya) for much less. So military action just seems very likely. (Involving all of NATO or not, as michel says.)
“A Russian nuclear strike would change the course of the conflict and almost certainly provoke a “physical response” from Ukraine’s allies and potentially from the North Atlantic Treaty Organization, a senior NATO official said on Wednesday.
Any use of nuclear weapons by Moscow would have “unprecedented consequences” for Russia, the official said on the eve of a closed-door meeting of NATO’s nuclear planning group on Thursday.
Speaking on condition of anonymity, he said a nuclear strike by Moscow would “almost certainly be drawing a physical response from many allies, and potentially from NATO itself”.
“-Reuters
I have heard of talk that the US might instead arm Ukraine with tactical nukes of its own, although I think that would be at least comparably risky as military retaliation.
The reasoning is that retaliating is US doctrine—they generally respond to hostile actions in-kind, to deter them. If Ukraine got nuked, the level of outrage would place intense pressure on Biden to do something, and the hawks would become a lot louder than the doves, similar to after the 9/11 attacks. In the case of Russia, the US has exhausted most non-military avenues already. And US is a very militaristic country—they have many times bombed countries (Syria, Iraq, Afghanistan, Libya) for much less. So military action just seems very likely. (Involving all of NATO or not, as michel says.)
“A Russian nuclear strike would change the course of the conflict and almost certainly provoke a “physical response” from Ukraine’s allies and potentially from the North Atlantic Treaty Organization, a senior NATO official said on Wednesday.
Any use of nuclear weapons by Moscow would have “unprecedented consequences” for Russia, the official said on the eve of a closed-door meeting of NATO’s nuclear planning group on Thursday.
Speaking on condition of anonymity, he said a nuclear strike by Moscow would “almost certainly be drawing a physical response from many allies, and potentially from NATO itself”. “-Reuters
https://news.yahoo.com/russian-nuclear-strike-almost-certainly-144246235.html″
I have heard of talk that the US might instead arm Ukraine with tactical nukes of its own, although I think that would be at least comparably risky as military retaliation.