Jesse Sanchez4 said:Partly joking and partly serious, I suspect one of the primary reasons is simply that we've witnessed enough Russian missiles falling out of the sky like ripe fruit due to sheer technical failure; it wouldn't be particularly wise to trigger a nuclear event right at the launch site.
Tactical nukes are meant for high-priority targets on the front lines. But let's be real, the Ukrainians have spread their military assets and supply depots all over the place—it's smart, really. It makes hitting them much easier with cruise missiles instead. If, for instance, the Russians tried using nukes during a massive Ukrainian push toward Kherson, they'd have to deploy multiple smaller warheads just to cover such a wide area. And then you run into the fallout problem. You can't exactly control where that radioactive dust drifts when the Ukrainians are the ones initiating the attack; the attacker dictates the timing, which means you're at the mercy of whatever the weather decides to do.
The Russians could potentially use strategic bombs to, say, blockade Kyiv.
But if they did that, they'd be looking at total global isolation. We'd also be staring down the possibility of NATO providing nuclear weapons to the Ukrainians.