I think that tactical nuclear weapon can hardly provide more serious devastation than what have been done in weeks and months of relentless shelling to some cities of Eastern Ukraine. My favourite example so far is Maryinka. Looking at this place from the sky, one may easily mistake it for the ground zero of small-size nuclear ammo detonation.

Though, of course, today Ukraine lacks similarly fortified redoubts near the frontline: it took some 2 years for Russians to claim it, whereas in Avdeevka the final stage of the siege has been completed in half a year, and now we see pretty quick advance in Krasnogorovka, Chasov Yar, and across the formal Ukrainian border north of Kharkov. Of course, all of it could, and should, be prevented by means of diplomacy; however, too wide was the circle of those who are very interested in conflagration of war.