The transcript of our conversation has been condensed, but is otherwise unedited.

James Fallows: Back when Mitt Romney was running against Barack Obama in 2012, he was widely ridiculed for saying that the No. 1 strategic challenge for the United States was Russia—rather than, say, China, or international terrorism. Was he right then? Has he become right, now?

Bill Burns: As usual, the picture is more complicated than whether this or that threat is “No 1.”

I think Putin has given ample evidence that Russia can be threatening in lots of different ways that matter to us, and to our friends and allies, and to the international order. President Obama, for whom I have very high regard, kind of dismissively observed that Russia is just a regional power. Well, it’s a pretty goddamn big region, across 11 time zones. And even as a declining power Russia can exert a fair amount of influence, often negative influence, on the landscape.

So it’s a mistake to be dismissive of that, and of course also a mistake to exaggerate it. And clearly, we have to take extremely seriously what Putin did in 2016.

William J. Burns: How the U.S.-Russian relationship went bad

Fallows: How exactly would you describe “what Putin did in 2016”?

Burns: I think he set out to do several things. The first was to sow chaos in the American political system. It was a target-rich environment for him, because our own dysfunction created lots of opportunities. While I would never understate the seriousness of the threat or of his actions, the truth is he was able to act like the good judo expert, which he is. He was able to use leverage over a stronger opponent—and that leverage was the polarization and dysfunction in our own system. He set out quite deliberately to sow further dysfunction, sow chaos.

Second, he loves exposing what he believes to be the hypocrisy of democratic systems. Anything that he could bring to light that would expose the seamier side of American politics was all to the good, from his point of view. And third, he wanted to put his thumb on the scale against Hillary Clinton—who, I think he assumed, like lots of Americans, was likely to win the election. I think on Election Night he was as surprised as Donald Trump was by Trump’s victory. But he clearly set out to put his thumb on the scale against Clinton, and also for Trump—even if he didn’t think Trump was going to win. Now, what else may have lain behind that, in terms of what Special Counsel Robert Mueller is investigating, we’ll see.

Fallows: In the two-plus years since the election, as events have unfolded under Trump, is Putin happy with the results? Or has he gotten more than he bargained for?

Burns: The chaos in foreign policy—which has only accelerated in terms of the predictability of America’s role in the world—is from the Russian perspective a double-edged thing.