Observers have put forward varying explanations suggesting that Russian President Vladimir Putin hopes, through nuclear threats, to achieve some current or future tactical edge in his face-off with Ukraine and NATO. But none of that reasoning erases a dangerous reality: Any Russian use of tactical nuclear weapons would create unprecedented conditions that could easily lead not to Russia's advantage, but to a wider nuclear war that would decimate Russia—and its leadership. Observers have put forward varying explanations suggesting that Russian President Vladimir Putin hopes, through nuclear threats, to achieve some current or future tactical edge in his face-off with Ukraine and NATO. But none of that reasoning erases a dangerous reality: Any Russian use of tactical nuclear weapons would create unprecedented conditions that could easily lead not to Russia's advantage, but to a wider nuclear war that would decimate Russia—and its leadership.