His [Trump's] cavalier attitude about nuclear weapons is so deeply troubling. That is the number-one threat we face in the world. And it becomes particularly threatening if terrorists ever get their hands on any nuclear material. So a man who can be provoked by a tweet should not have his fingers anywhere near the nuclear codes, as far as I think anyone with any sense about this should be concerned.

We're talking about a man who has control of the largest nuclear arsenal in the world. That makes him more dangerous than... other people, because he has the nuclear codes.

The responsibility for the control of U.S. nuclear weapons rests solely with the President, who exercises the control of their use in all foreseeable circumstances. This has been the case since 1945, under four Presidents. It will continue to be the case as long as I am President of the United States. In this atomic age we have always been required to show restraint as well as strength. At moments of decisive tests, our nuclear power has been essential. But we have never rattled our rockets or come carelessly to the edge of war.

What I admire most about Hillary is that she never buckles under pressure. She never takes the easy way out. And Hillary Clinton has never quit on anything in her life. And when I think about the kind of president that I want for my girls and all our children, that is what I want. I want someone with the proven strength to persevere. Somebody who knows this job and takes it seriously. Somebody who understands that the issues of our nation are not black or white. It cannot be boiled down to 140 characters. Because when you have the nuclear codes at your fingertips and the military in your command, you can't make snap decisions. You can't have thin skin or a tendency to lash out. You need to be steady and measured and well informed.

Look, having nuclear—my uncle was a great professor and scientist and engineer, Dr. John Trump at MIT; good genes, very good genes, OK, very smart, the Wharton School of Finance, very good, very smart—you know, if you're a conservative Republican, if I were a liberal, if, like, OK, if I ran as a liberal Democrat, they would say I'm one of the smartest people anywhere in the world—it's true!—but when you're a conservative Republican they try—oh, do they do a number—that's why I always start off: Went to Wharton, was a good student, went there, went there, did this, built a fortune—you know I have to give my like credentials all the time, because we're a little disadvantaged—but you look at the nuclear deal, the thing that really bothers me—it would have been so easy, and it's not as important as these lives are—nuclear is powerful; my uncle explained that to me many, many years ago, the power and that was 35 years ago; he would explain the power of what's going to happen and he was right, who would have thought?—but when you look at what's going on with the four prisoners—now it used to be three, now it's four—but when it was three and even now, I would have said it's all in the messenger; fellas, and it is fellas because, you know, they don't, they haven't figured that the women are smarter right now than the men, so, you know, it's gonna take them about another 150 years—but the Persians are great negotiators, the Iranians are great negotiators, so, and they, they just killed, they just killed us.

A man you can bait with a tweet is not a man we can trust with nuclear weapons.

You know, nothing truly prepares you for the demands of the Oval Office. You can read about it. You can study it. But until you’ve sat at that desk, you don’t know what it’s like to manage a global crisis, or send young people to war. But Hillary has been in the room; she’s been part of those decisions. She knows what’s at stake in the decisions our government makes — what’s at stake for the working family, for the senior citizen, or the small business owner, for the soldier, for the veteran. And even in the midst of crisis, she listens to people, and she keeps her cool, and she treats everybody with respect. And no matter how daunting the odds, no matter how much people try to knock her down, she never, ever quits. That is the Hillary I know. That’s the Hillary I’ve come to admire. And that’s why I can say with confidence there has never been a man or a woman — not me, not Bill, nobody — more qualified than Hillary Clinton to serve as president of the United States of America.

Representative Tulsi Gabbard has made reforming United States foreign policy, particularly ending what she calls “regime change wars” and the “new Cold War and nuclear arms race,” central to her 2020 presidential campaign. She is virtually the only presidential candidate warning of the specter of nuclear war. At a CNN town hall at South By Southwest on March 10, Gabbard contended, “We are in a situation today where we, here in the United States and the world, are at a greater risk of nuclear catastrophe than ever before in history.”

"I wish it were different. I wish that we privileged knowledge in politicians, that the ones who know things didn't have to hide it behind brown pants, and that the know-not-enoughs were laughed all the way to the Maine border on their first New Hampshire meet and greet. I wish that in order to secure his party's nomination, a presidential candidate would be required to point at the sky and name all the stars; have the periodic table of the elements memorized; rattle off the kings and queens of Spain; define the significance of the Gatling gun; joke around in Latin; interpret the symbolism in seventeenth-century Dutch painting; explain photosynthesis to a six-year-old; recite Emily Dickinson; bake a perfect popover; build a shortwave radio out of a coconut; and know all the words to Hoagy Carmichael's "Two Sleepy People," Johnny Cash's "Five Feet High and Rising," and "You Got the Silver" by the Rolling Stones. After all, the United States is the greatest country on earth dealing with the most complicated problems in the history of the world — poverty, pollution, justice, Jerusalem. What we need is a president who is at least twelve kinds of nerd, a nerd messiah to come along every four years, acquire the Secret Service code name Poindexter, install a Revenge of the Nerds screen saver on the Oval Office computer, and one by one decrypt our woes."

Hillary Clinton is a clear and present danger to the Constitution, the rule of law, and international peace and security. Her eagerness for war, i.e., legalized murder, to create an image of adolescent toughness makes her a worse fit for the Presidency than would .

Donald Trump tells us that he is very, very smart. I'm afraid that when it comes to foreign policy he is very, very not smart.

I wish that in order to secure his party’s nomination, a presidential candidate would be required to point at the sky and name all the stars; have the periodic table of the elements memorized; rattle off the kings and queens of Spain; define the significance of the Gatling gun; joke around in Latin; interpret the symbolism in seventeenth-century Dutch painting; explain photosynthesis to a six-year-old; recite Emily Dickenson; bake a perfect popover; build a shortwave radio out of a coconut; and know all the words to Hoagy Carmichael’s “Two Sleepy People”, Johnny Cash’s “Five Feet High and Rising”, and “You Got the Silver” by the Rolling Stones...What we need is a president who is at least twelve kinds of nerd, a nerd messiah to come along every four years, acquire the Secret Service code name Poindexter, install a Revenge of the Nerds screen saver on the Oval Office computer, and one by one decrypt our woes.

Those of you who are deeply committed to peace, don't worry about that, about military strength. Our weapons, our military forces, men and women, will never be excelled by any other nation on Earth. We're in the cutting edge of progress. And our strategic nuclear weapons and our conventional weapons, our Navy, our men and women, are strong, and they're going to stay strong. But an airplane doesn't fly on just one wing. With that powerful military strength, you've got to have two more things. One is a commitment to arms control, because we don't want to have a nuclear arms race in this world. Every President since Harry Truman has insisted upon balanced, equivalently equal, controlled, observable arms control treaties. Recently, as you know, my opponent said, let's throw the arms control treaty in the trash, and let's start an arms race or threaten an arms race against the Soviet Union, to play a trump card against them. That's a radical departure from what all Presidents have done, Democratic and Republican, since the Second World War. It's important to us as a nation, it's important to our allies and friends, like Israel and the Middle East, to make sure that Iraq and other countries of a radical nature do not have military weapons that are nuclear explosives. We've had a very strong nonproliferation policy under Democrats and Republicans, but Governor Reagan says that nonproliferation is none of our business. The issues are clearly drawn, not only about the past and present but also about the future. We now have a sound energy policy to give us a basis on which to revitalize American industry, to have modern tools and modern plants for American workers, to put all our people to work; to have better health care for our citizens, more preventive health care, catastrophic health insurance, better care for pregnant women and little babies, better care for elderly citizens, more outpatient care rather than inpatient, the holding down of hospital costs. These changes in our health program can be implemented with a national health insurance plan. I'm for it, Democrats are for it; Governor Reagan's against it.

We made our mistakes back in the 20th century, Lord knows, but we never nominated a man for president who brags about not reading. Calvin Coolidge had his limits. Warren G. Harding spent more time on his hair than strictly necessary. Lyndon Baines Johnson was a piece of work. But all of them read books. When I envision a Trump Presidential Library, I see enormous chandeliers and gold carpet and a thousand slot machines. God help us. I mean it. We’re in trouble down here.