From the New York Times, I'm Sabrina Tavernici, and this is The Daily.

If Vladimir Putin ever follows through with his threat to use a nuclear weapon in Ukraine,

he's likely to use a very particular kind of nuclear weapon.

Today, I talked to my colleague Bill Broad on what that weapon is, how it works, and what it would mean to deploy it.

It's Friday, October 7.

So Bill, two weeks ago, we did an episode with our colleague Anton, and he told us that Putin had effectively declared a chunk of Ukraine Russian territory, and he said that if it was attacked, he would fight back.

And he kind of hinted that he would use his nuclear arsenal.

So this whole week, the Ukrainians are making a lot of military advances in that very area that Putin was talking about.

And so everyone, I'm in DC here, is talking about this and kind of on edge.

Are we in a new, more dangerous moment in the world?

So we wanted to ask you, Bill, what would an attack like this look like?

I mean, when I think of nuclear weapons, I think of a mushroom cloud. Is that what we're talking about?

We're not. Although that tends to be the thing that, you know, we all conjure up in our minds, right?

These big, horrible things we saw one over Hiroshima. We've seen pictures of tests around the globe where these frightening, huge things would scare and intimidate everybody into all these unthinkable scenarios.

What we're talking about now is extremely different. It's a whole different dark universe that grew up in parallel to this ginormous, scary world of mushroom clouds.

Okay, different universe, they grew up in parallel. So tell me about that, Bill. I mean, how are the nuclear weapons of today different from the ones that we haven't remained?

They're fundamentally much, much, much, much smaller. They call them tactical nukes.

They are tiny fractions of the strength of the Hiroshima bomb and tiny, tiny little fractions of the super bombs and the city busters that everybody worried about during the Cold War.

In comparison to all that and to everything we've known and thought about publicly for a long time, they are minuscule.

So how do these smaller ones in this new world you're talking about come to be?

Well, they all grew out of the very first atomic weapons. The one we all remember was Hiroshima. Right, 1945 ended World War II.

The city of Hiroshima lies plus straight after the weathering blast which wiped out 53,000 of its population.

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