Anytime the words “Donald Trump” and “nuclear weapons” appear in the same sentence, a mushroom cloud of anxiety rises over the world of politics and national security.

Wednesday was no exception, after Joe Scarborough, host of MSNBC’s “Morning Joe,” said on his show that Trump had repeatedly asked an unnamed foreign policy expert why the U.S. can’t use its nuclear weapons.


The notion that Trump might be entertaining a more liberal nuclear-strike policy renewed alarms among national security experts in both parties about the GOP nominee’s fitness to be commander in chief. “Trump would be undoing 6 decades of proven deterrence theory. The purpose of nukes is that they are never used. Trump disagrees?” tweeted John Noonan, a former national security adviser to Jeb Bush’s campaign. “This would be the single greatest strategic shift in US national security in decades,” added Noonan, a former Minuteman missile operator.

Trump officials denied Scarborough’s account, and the host didn’t identify his source for the claim that Trump had asked, three times, “If we have them, why can’t we use them?” But the claim rang true for those who have followed Trump’s comments about nuclear weapons, which many experts call dangerously glib and uninformed, and which play into the Democratic strategy of portraying him as unfit to handle the nuclear codes.

That seemed clear from a new Fox News poll released Wednesday showing that 56 percent of voters believe that Clinton would make better decisions about nuclear weapons, with just 34 trusting Trump more.

Trump has repeatedly declined to rule out the use of nuclear weapons, saying he reserves the option to use them in Europe and the Middle East. Trump has also said he might welcome seeing certain U.S. allies, including Japan, acquire atomic arms to better defend themselves without U.S. assistance.

During a March appearance on MSNBC’s “Hardball,” Trump demurred when the show’s host, Chris Matthews, pressed him to rule out nuclear strikes.

“Can you tell the Middle East we’re not going to use a nuclear weapon on anybody?” Matthews asked.

“I would never say that. I would never take any of my cards off the table,” Trump replied. "Look, nuclear should be off the table. But would there be a time when it could be used? Possibly, possibly."

When asked a similar question about Europe on Fox News the next day, Trump replied: “Europe is a big place. I’m not going to take cards off the table.”

Trump also seemed to tell Matthews that he might retaliate against an attack by the Islamic State, also known as ISIS, with a nuclear bomb.

“Somebody hits us within ISIS, you wouldn’t fight back with a nuke?” Trump asked.

“He talks about nuclear weapons very loosely, casually—as if they’re just another tool in the toolbox,” said Joe Cirincione, president of Ploughshares Fund, a nonprofit that advocates nuclear arms reductions.

While Trump’s comments have drawn widespread condemnation, they do not defy America’s nuclear doctrine, which reserves the right to use nuclear weapons—even as a “first strike” against an adversary fighting with only conventional weapons.

There are some exceptions: The Obama administration has said it will “not use or threaten to use” nuclear weapons against non-nuclear weapons states that have signed and are in compliance with the nuclear nonproliferation treaty.

“The U.S. does not rule out the use of nuclear weapons,” said Anthony H. Cordesman, a military analyst with the Center for Strategic and International Studies. “But we give primary emphasis to conventional options. We have made it clear historically that we’d be extremely reluctant to use nuclear weapons. We’d have to be forced into it by truly dire circumstances.”

Trump does say that he is highly averse to the nuclear option: “The last person to use nuclear would be Donald Trump ... The thought of it is horrible,” he told Matthews in March.

But he does not discuss the issue with the nuance of foreign policy experts and insiders, who choose their words with extreme care, and, when possible, avoid discussing nuclear strikes entirely.

Trump has also unnerved observers with his apparent unfamiliarity with U.S. nuclear doctrine. When asked during a December primary debate whether he would eliminate any part of the so-called nuclear triad — which consists of land, air and sea-based weapons — Trump seemed unaware of the concept.

“We have to be extremely vigilant and extremely careful when it comes to nuclear. Nuclear changes the whole ballgame,” Trump said. “I think to me, nuclear, is just the power, the devastation is very important to me,” he concluded.

Trump’s defense of the right to use nuclear weapons also comes at a time when President Barack Obama is considering issuing an executive order that would change U.S. policy to rule out the first use of a nuclear weapon.

Hillary Clinton’s campaign squarely targeted the concept of a nuclear-armed Trump during last week’s Democratic National Convention. “A man you can bait with a tweet is not a man we can trust with nuclear weapons,” Clinton said in her nomination acceptance speech, echoing several other speakers.

And since mid-June the pro-Clinton Super PAC Priorities Action USA has been airing an advertisement that features audio of Trump saying, “I love war, in a certain way,” immediately followed by a different clip in which Trump says, “including with nukes, yes, including with nukes.”

Clinton advisers say they believe the prospect of Trump commanding America’s arsenal of 7,200 atomic weapons is a highly effective way of crystallizing voter anxieties about the New York mogul’s temperament.

While nuclear weapons provide a powerful psychological deterrent against enemies, modern conventional weapons can inflict the same damage as atomic ones with no radioactive fallout and no erosion of post-World War II norms against atomic combat.

Cirincione ridiculed the idea of striking ISIS with a nuclear bomb, noting the massive civilian deaths certain to come with an attack on a target like the Syrian city of Raqqa, ISIS’ unofficial capital. “You don’t win by using a nuclear weapon — you lose.”

But he also noted with concern that a president has unilateral power to initiate a nuclear launch without consulting others, though military officials in the chain of command below him could theoretically challenge his order.

“The president has absolute authority to use a nuclear weapon any time he wants. Once a command is given it is automatically implemented, short of a large scale mutiny,” Cirincione said.

“A president Trump could get very upset about something he sees on television and decide to launch. It would take a minute to call the [military] officer. Minutes to input the codes. Minutes more to launch the missiles. The process is designed to be rapid and automatic. It’s not designd for debate, contemplation, reconsideration or democracy,” he said.