Donald Trump's confusing comments about nuclear weapons in Monday night's debate are not the first time during this presidential campaign that his statements have left nuclear experts wondering just what he might do if he gains access to the nuclear football.
On Monday, Trump agreed with moderator Lester Holt that nuclear weapons are of paramount importance to the U.S. — but then called for more nations to join the nuclear club. He ruled out a "first strike," but then revealed not just a willingness to use nukes but also a misunderstanding of the high-stakes balancing act the nuclear superpowers have pursued for decades.
"I think that once the nuclear alternative happens, it's over," Trump said, referring to the use of nuclear weapons. "At the same time, we have to be prepared. I can't take anything off the table. Because you look at some of these countries, you look at North Korea, we're doing nothing there."
The United States, under both Democratic and Republican administrations, has worked closely with partners in China and Russia to halt the advance of North Korea's illegal capability.
Trump's performance Monday night also suggested he may not know the difference between "first use" and "first strike."
He responded to a question from Holt about "first use" with a statement about a "first strike."
"I would like everybody to end it, just get rid of it," he said of nuclear weapons. "But I would certainly not do first strike."
Though the phrases sound alike, "first strike" refers to a nuclear power initiating nuclear combat and landing the first blow — traditionally, the U.S. or Russia. Since the beginning of the Cold War, the threat of a first strike has been the "balance of terror" that holds each side's nuclear capabilities in check.
"First use" is an un-official U.S. prohibition on the use of nuclear weapons against enemies who don't have nuclear capability.
Joseph Cirincione, president of the Ploughshares Fund, said Trump's comments are typical of his public statements on nuclear weapons policy.
"Donald Trump is very cavalier about how he talks about nuclear weapons," said Cirincione. "He treats them as if they are another tool in the toolbox."
Trump's comments Monday were the latest in a series of statements that critics, including Cirincione, have called troubling.
The most famous came in a Republican presidential candidate debate on CNN back in December 2015.
Conservative pundit Hugh Hewitt asked Trump about the nuclear triad — the air, sea and land-based nuclear weapons arrangement that ensures the U.S. will have surviving forces that can respond effectively to a nuclear attack. The triad is meant to deter an enemy from attempting a strike in the first place and has been at the center of the U.S. strategic policy for a half century.
Trump seemed unaware of what the triad entails and responded instead with an attack on President Obama.
"The biggest problem this world has today is not President Obama with global warming, which is inconceivable; this is what he's saying. The biggest problem we have is nuclear — nuclear proliferation and having some maniac, having some madman go out and get a nuclear weapon."
When Hewitt failed on a second attempt to get Trump to comment on the triad, he turned instead to Sen. Marco Rubio, who explained the triad in accurate terms.
In May, Trump even suggested he could support South Korea, Japan and Saudi Arabia, who are not currently nuclear powers, arming themselves with nuclear weapons for their own defense.
CNN's Anderson Cooper asked the Republican presidential nominee, "So if you said, Japan, yes, it's fine, you get nuclear weapons, South Korea, you as well, and Saudi Arabia says we want them, too?"
"Can I be honest with you? It's going to happen, anyway. It's going to happen anyway. It's only a question of time," Trump insisted, despite a 25-year trend in which numerous nations — Libya, South Africa, Iraq, and former Soviet republics — have been denuclearized.
"They're going to start having them or we have to get rid of them entirely," Trump said. "But you have so many countries already, China, Pakistan, you have so many countries, Russia, you have so many countries right now that have them."
Cirincione said that Trump, who uses business parallels in many of his policies, is wrong on the pursuit of proliferation.
"What is the parallel here?" asked Cirincione. "In the business world, competition is good; in nuclear arms, it's not."
Trump has also discussed the use of nuclear weapons on the battlefield rather than seeing them purely as a deterrent. In March, he told Bloomberg News he would want to be "unpredictable" in nuclear decision making, citing the war against ISIS.
Mark Halperin of Bloomberg asked: "So you would — you would rule out the possibility of using, right, nuclear weapons against ISIS?" Trump responded: "Well, I'm never going to rule anything out."
Around the same time, when discussing nuclear weapons with Chris Matthews of MSNBC, Trump said basically the same thing.
"Somebody hits us within ISIS — you wouldn't fight back with a nuke?"
When Matthews pressed Trump about how U.S. allies like Japan don't like to hear a U.S. president muse aloud about the use of nuclear weapons, Trump again was dismissive of the concerns.
"Then why are we making them? Why do we make them?"
In March, he told Eric Bolling of Fox News that he wouldn't rule out using nuclear weapons in Europe. The first Bush administration largely denuclearized U.S. military forces, leaving only a token force on the continent.
"The last person that wants to play the nuclear card believe me is me. But you can never take cards off the table either from a moral stand — from any standpoint and certainly from a negotiating standpoint. … Europe is a big place. I'm not going to take cards off the table," Trump said.
Cirincione said there is a vibrant academic debate on the future of nuclear weapons and the modernization of the U.S. arsenal, but that debate doesn't seem to be influencing Trump.
"He understands something, that there is something special about them, but what he has to understand is what's beyond [that]; their awesome destructive power," he said.
"He doesn't understand their role in our security policy. What he's saying? He argues purely from a good gut instinct. Is that the way you make nuclear policy?"
Cirincione says there is a need for a national discussion of some of the issues Trump brought up Monday, like modernizing the aging arsenal. But he also argues that Trump's statements are outside the mainstream of both parties. He notes that presidents from Harry Truman to George H. W. Bush have been advised by military commanders to use nuclear weapons, but presidents have refused.
"It is an awesome responsibility," he said.