We now have an idea what prompted Secretary of State Rex Tillerson to call President Donald Trump a “moron”: NBC News is reporting that Trump had spoken openly in the preceding meeting with national security leaders about a return to a Cold War footing with nuclear weapons — what would amount to about a tenfold increase:

“Trump’s comments, the officials said, came in response to a briefing slide he was shown that charted the steady reduction of U.S. nuclear weapons since the late 1960s. Trump indicated he wanted a bigger stockpile, not the bottom position on that downward-sloping curve.

“According to the officials present, Trump’s advisers, among them the Joint Chiefs of Staff and Secretary of State Rex Tillerson, were surprised. Officials briefly explained the legal and practical impediments to a nuclear buildup and how the current military posture is stronger than it was at the height of the build-up. In interviews, they told NBC News that no such expansion is planned.”

It was after this July 20 meeting that Tillerson reportedly offered his “moron” comment — something the State Department has pretty directly denied, even as Tillerson declined to do so personally.

This is hardly the first time Trump has talked flippantly and/or unrealistically about nuclear weapons. But it does reinforce that his attitude toward them, which leaders clearly regard as amateurish and foolhardy, is seeping into official White House business. While Trump’s loose chatter about nukes might have been dismissed as campaign bluster and posturing before, it seems much more real now.

Trump is disputing NBC’s story.

As a candidate, Trump seemed to shy from nuclear weapons at times, saying the “biggest problem, to me, in the world, is nuclear, and proliferation.” He said using such weapons would be an “absolute last step.” He added in April that, “I will be the last to use nuclear weapons. It’s a horror to use nuclear weapons.”

But around the same time, he flirted with the idea of actually allowing more countries — namely Japan — to have nuclear weapons. “Can I be honest are you? Maybe it’s going to have to be time to change, because so many people, you have Pakistan has it, you have China has it,” he said. “You have so many other countries are now having it.”

By August 2016, MSNBC host Joe Scarborough claimed that Trump had asked a foreign policy expert what good nuclear weapons were if they weren’t utilized. “Several months ago, a foreign policy expert on the international level went to advise Donald Trump,” said Scarborough, who was intermittently friendly and adversarial with Trump. “And three times, Trump asked about the use of nuclear weapons. Three times. He asked at one point, if we had them, why can’t we use them?”

The Trump campaign denied this. But in a March interview on MSNBC, Trump seemed to make a similar argument.

“CHRIS MATTHEWS: The Japanese, where we bombed them in ’45, heard it. They’re hearing a guy running for president of the United States talking of maybe using nuclear weapons. Nobody wants to hear that about an American president.

“TRUMP: Then why are we making them? Why do we make them?”

And twice in early 2016, he said he wanted to be “unpredictable” with nukes, including leaving open the idea of using them in Europe if necessary. “Europe is a big place,” he said.

As president, Trump’s comments about nukes have also resulted in some head-scratching. Back in August, Trump falsely claimed that the arsenal was “far stronger and more powerful than ever before” thanks to upgrades made on his watch. That came despite those upgrades having been virtually impossible in his short time in office and the fact that the U.S. has a fraction of the weapons it once did.

Nuclear weapons also seemed to seep into Trump’s repeated threats to attack North Korea if necessary. At one point he said he would “totally destroy” North Korea if Kim Jong Un forced him to defend the U.S. or its allies — a threat that logically would suggest the use of nuclear weaponry.

On some level, this completely plays into Trump’s foreign policy strategy. I’ve written before about how Trump is fond of the “madman strategy” in which you make your foes believe you are capable of pretty much anything. The White House even seemed to agree with that characterization on Friday:

“Q: There’s a theory in Washington — and forgive me if you’ve been asked about it before — that the president subscribes to this madman theory. That if he makes a lot of unsettling, off-putting comments, that sort of throw people off, that he likes to keep his adversaries guessing. That that’s sort of the point of making comments like “calm before the storm” and so forth. What is your sense of that? Is there — is there anything to that? Is there …”

“SARAH HUCKABEE SANDERS: I think the president’s addressed this himself. He certainly doesn’t want to lay out his game plan for our enemies. So if you’re asking, is the president trying to, you know, do that, absolutely.”

In that way, Trump may not be terribly upset about the new NBC report; he may even like it. But judging by how Tillerson responded to it – and by how Senate Foreign Relations Committee Chairman Bob Corker, R-Tenn., recently suggested Trump could lead us into World War III – it’s clear that it’s giving those intimately involved in Trump’s foreign policy plenty of heartburn. That’s partially because they know how unrealistic it is, but it’s also partially because they worry about the eventual result.

David Petraeus recently expanded upon the downside of the madman strategy:

“There may, again, be some merit into the madman theory until you get in a crisis. But you do not want the other side thinking you are irrational in a crisis. You do not want the other side thinking that you might be sufficiently irrational to conduct a first strike or to do something, you know, so-called ‘unthinkable.'”

That seems to be what Corker is worried about, and comments like this won’t allay those fears.

Aaron Blake wrote this for The Washington Post.