Correct, hence the entire reason I suggested the qualifier of practical. Nuclear attacks are clearly impractical by any sane individual, but in terms of strength and damage, aside from some sort of biological weapon, I'm not sure what could have similar impact.

Forget nuclear contamination. If Russia nukes a NATO country, nukes are coming back to land on Russia. And Putin, personally, will die, and so will Russia as a nation.

So, it was an impressive threat. I doubt he actually would follow through... but he might. That's his leverage - that we wonder if he might. Rationally, though, it's a crummy threat, because rationally his own downside is far too big.