If they're lobbing any, they're probably lobbing most anyways.

When I took a class on strategic nuclear game theory back in the 80s the options were 1, 2 and all, with "all" being the only serious cases. The assumption was the enemy would try to take out all your nukes so you'd have to launch quickly before they were taken out.

Subs, of course, being the ultimate terror weapon, changed the calculus completely. What I really got out of the class was that this kind of game theory was almost useless once you had subs with nukes on them.

"Almost" because antimissile defense was destabilizing even without subs, so is in everybody's interest to negotiate away.

MAD is a scenario, not the only or most likely. There are a million and one scenarios where you have some kind of nuclear conflict and it stays regional. And actually this part is a massive problem for the US since we don’t have a viable tactical nuclear arsenal.

Our strategic options are limited and the US wouldn’t be able to respond tit-for-tat if, say, the Russians started using smaller weapons in a battlefield situation, our only option is to either do nothing, or level a city and escalate the conflict.

What about B61s do you think are unviable? Or is it the lack of missile systems that you're considering is unviable?

B61s are aircraft delivered gravity bombs, a relic of the 1960s. It’s an entirely different category compared to the short range ICBMs that Russia employs from mobile ground vehicles.

Yes, it's a totally different category from SRBMs - so maybe the US's ability to deliver tactical nuclear weapons more than 10-100km into highly contested airspace is poorer, but given your original scenario (battlefield use and tit for tat vs Russia), I don't see this being a significant limitation?

As it stands today, I have no reason to believe that American aircraft (F-35 and B-2 both carry B-61) cannot conduct operations over the forward areas of Russian ground forces.

Ukraine has been able to use GMLRS and, launch cruise missile strikes into Russian held territory success. Ukraine believes that ATACMS will be viable. I don't believe the current evidence indicates that Russian IADS are capable of sufficiently deflecting/deterring an American air strike.

This was not considered "strategic" decision making back in the 80s, but I see your point. I do think it's good the US junked its tactical nuke programs (Davy Crocket et al) because they are tricky and hard to find good use cases for. They are also hard not to lose (most people don't realize how many portable things get lost in combat).

Allegedly Russia has various "red lines" which, when crossed would lead to tactical nukes in the Ukraine theatre. Many of those lines have been crossed with no nuke use. Prof Phillips P. OBrien pointed out that tactical nukes at this point would be an admission of weakness and would turn many allies against Russia. Also, like chemical weapons, they are simply hard to use without interfering with your own troops. Probably, IMO, the only use case is on day 0 right at the initial invasion.

The US has a wide range of non-weaponry responses, and who knows what they have in their subs, They may have smaller scale nukes as well. Subs are destabilizing today because nobody knows where they are. They used to be destabilizing because that also meant they were inaccurate (thus only useful against cities, where, like the game of horseshoes, "close" is good enough). Nowadays once they are launched they can use GPS, the stars, and probably simply vision since they know the approximate launch and destination locations.

You're currently getting downvoted which seems unreasonable.

Only launching one 10th of their warheads? What are the saving the other 90% for, exactly? The next nuclear war? A rainy day?