On Thursday, NATO's senior body on nuclear matters made it clear that any nuclear attack by Russia would provoke serious retaliation.
The consequences for Russia would be unprecedented, they said, and would almost certainly draw a military response.
I believe that's true, and I think Vladimir Putin does too. And that's just one of the many reasons I think we'll avoid a live nuclear war.
But that doesn't mean we're going to avoid war with Russia. Because the truth is we're already at war with Russia.
That's not just my opinion, either.
It's something that's now being acknowledged at the highest levels of our respective governments.
"The post-Cold War era is definitively over and a competition is underway between the major powers to shape what comes next," the Biden administration declared in its official National Security Strategy brief.
Meanwhile, with regard to Ukraine specifically, Russian Foreign Minister Sergei Lavrov says "the Americans have been participating in this war for a long time."
"This war is being controlled by the Anglo-Saxons," he told Russia's state TV.
Obviously, that last bit isn't true. That's some Soviet-style propaganda. But the first part is indisputable.
Since Russia invaded Ukraine in February, the United States has deployed $15 billion in aid. That includes some of the most fearsome and effective war-fighting technology we have to offer - weapons that have turned the tide of the war.
In fact, those weapons and the Ukrainians wielding them have been so effective that Russia has resorted to retaliating with non-conventional warfare.