And each of the several Russian missiles fired in response to this single futile effort would be much more powerful than the Fat Man with thousands of missiles still held in reserve.
Unless the Russian response is extraordinarily disproportionate, the Western response is likely some stern talk to the Russians and a statement to the Ukraine saying that was a stupid move on your part and you'd be wise to end this war now.
Are we SURE about that? Seriously. Russia has the same reputation as China when it comes to honesty, and when it comes to proper maintenance of older equipment. Russia doesn't have any new nukes, and their military budget is one eleventh the size of ours. AND they've been losing men and materiel for 2 years now, while failing to take Kiev. They need to spend money on maintaining and replacing those losses, they need to spend money and resources on pretending to have a military that compares to ours, AND they're going to maintain the largest number of warheads on earth??? (5500 to our 5000). On only 9% of our budget???
Color me highly skeptical that they have more than a handful of VIABLE nuclear missiles. They seem a lot more like a paper tiger thees days, while getting their tails kicked by an unarmed Ukraine.