That doesn't mean that we like it or approve of it, but that it was rational.

Can you fill us in on your thinking about this?

Because it goes to the heart of the issue I raised about whether or not those leaders after the Second World War would have been wiser in their approach to it. Maybe we've just become too smug and too slow to read real politic.

I think that's exactly what happened here.

I think you have to go back to the 1990s to understand what's going on in Ukraine.

There was a big debate in the Clinton administration about whether to move NATO eastward, whether there would be NATO expansion or not.

And inside the Clinton administration, there were a good number of people who were adamantly opposed to expanding NATO.

Because they thought in realist terms, they believed that the Russians would see this as a threat.

And as NATO got closer and closer to Russia's borders, it would all blow up in our face.

And they fought tooth and nail to prevent it.

This included people like George Kennan.

It included Secretary of Defense Bill Perry, who has said he thought about resigning from the Clinton administration over this very issue. But these realists were opposed by a good number of liberals.

And this included the president himself, Tony Lake, who was his national security adviser, Richard Holbrook and a number of others who believed that NATO expansion was a good thing.

They had a more liberal mindset and thought that this would help promote democracy and economic prosperity in Eastern Europe.

It would not be threatening to the Russians because they would see us as a benign hegemon and we would live happily ever after. But what happened is the realists lost, the liberals won, and we started to expand NATO.

We got away with a big tranche of expansion first in 1999.

That's when Poland, Hungary, and the Czech Republic came in.

Then we got in way with another big tranche of expansion in 2004.

This is when the Baltic states, Romania, Bulgaria, Slovenia, Slovakia all came in.

But then in 2008, the trouble started, because in April 2008, we thought in terms of a third big tranche.

And this time we said explicitly that NATO was going to bring Georgia and Ukraine into the alliance.

The Russians made it unequivocally clear that this was not going to happen.

And Putin made it unequivocally clear at the time that it was a move that would lead to the destruction of Ukraine. Now, very importantly, John, at the NATO summit in Bucharest in April 2008, where this policy decision was made, Angela Merkel and Nicolas Sarkozy, the leaders respectively of Germany and France, were unequivocally opposed to bringing Ukraine into NATO.

And Angela Merkel has said that the reason that she was opposed was because she thought that Putin would view it as a declaration of war. So if you think about it here, you have all these policymakers and prominent individuals like Kennedy in the 90s.

And then you have Angela Merkel and Nicolas Sarkozy were saying this is not a smart thing to do.

And Bill Burns, who's now the head of the CIA and in April 2008 was the U.S. ambassador to Moscow, wrote a memo to Condoleezza Rice, then the secretary of state, basically telling her that this is the brightest of red lines and it's going to lead to unending trouble if we continue to pursue bringing Ukraine into NATO.

So there were a lot of people who were opposed, and I joined that bandwagon in effect, right, because I wrote this famous article in 2014 after the crisis in Ukraine broke out saying that it was the West's fault, in effect, for expanding NATO eastward. But what happened here is that we doubled down at every turn.

It's really quite remarkable.

After the crisis broke out in February of 2014, instead of backing off, re-evaluating the situation, we doubled down, and we have done that at every turn since then.

And the end result is that we're now in this horrendous war that turns one's stomach when you think of what is happening to Ukraine. And my bottom line here is that this decision to expand NATO into Ukraine was irresponsible in the extreme because of the consequences for the Ukrainian people, for the consequences that flowed from this decision for Ukraine as a functioning society.

I mean, it's being destroyed.

I believe this could have been avoided had we not expanded NATO or tried to expand NATO into Ukraine, had we backed off.

But we didn't do that.

And now we're paying the price.

Actually, to be clear, it's the Ukrainians who are really paying the price.

And this is what makes this such a terrible situation. Now, your point is that don't you think that if we had had the leaders who were in charge in the late 1940s and early 1950s, that they would have been more sagacious and that they would have avoided this disaster.

I think a good case could be made that that's true.

Again, you don't want to underestimate how many people have been opposed to this policy of bringing more and more countries, including Ukraine, into NATO from the get-go.

There's been a lot of resistance.

It's just that the other side has won at every turn.