Rand has issued an interesting study on the use of nuclear weapons in the event of Russian action in the Baltic. Among other things they note:
Despite its global advantages, the North Atlantic Treaty Organization
(NATO)'s current deterrent posture in the Baltic states is militarily
weak and generally questionable. A Russian invasion there would almost
surely capture some or all of those states' capital cities within a few
days, presenting NATO with a fait accompli. The United States is
currently considering tailored deterrence strategies, including options
to use nuclear weapons to deter Russian aggression in the Baltic states.
This report examines what role nonstrategic nuclear weapons could play
in deterring such an invasion. As part of that analysis, the authors
review relevant deterrence theory and current NATO and Russian nuclear
and conventional force postures in Europe. They draw on wargame
exercises and qualitative modeling to characterize the potential
outcomes if NATO, Russia, or both employ nonstrategic nuclear weapons
during a war in the Baltic states. The authors then discuss implications
for using such weapons to deter a Russian invasion. The insights
derived from the research highlight the reality that, even if NATO makes
significant efforts to modernize its nonstrategic nuclear weapons, it
would have much stronger military incentives to end a future war than
Russia would. That is, Russia would still enjoy escalation dominance.
I have spent some time in these states and they generally are small, easily accessible along the Baltic, and abut a small part of Poland, a larger section of Belarus, and on the east and west Russian territories.
Nuclear weapons are deadly, small or otherwise and their destructive potential are massive. The impact on surrounding countries and Russia itself would be horrendous.
Small yield tactical nukes have floated around US arsenals for decades. These are 1-5 KT "clean" weapons useful for field applications against a massive Soviet tank attack. These alleged "clean" weapons still result in massive amounts of radioactive products, albeit of shorter lasting time. Yet destruction would be massive.
It is worth reading through this document to see where current US and Russian thinking could be. Perhaps speaking with the Russians to avoid "ambiguity of expectations" would help. In my prior experience in the 70s on the CTBT it was clear that both sides were terrified as regards t an all out nuclear war and in my almost decade long working with the Russians the old fear remained. New generations of planners may have yet to face the terror of such weapons. Perhaps now is a good time to rethink the approach.