Summary: Legally the president makes the decision and everyone else then scurries around and follows his or her orders; in practice it's not going to be that simple in peace time especially. He or she doesn’t just have a button to press and the weapons fire; it’s a figurative expression. A president who gave that order in peacetime would surely be treated as temporarily deranged and ignored. They would need broad support, from their defense secretary especially.

However, in the event of an imminent attack on the US they decided that the president has to be able to launch a response within minutes. This is a result of the cold war and the idea of MAD (Mutually Assured Destruction). For that reason the president has been given authority to launch an attack on his or her own without consultation. That's the origin of their power to launch. But it's only meant for situations where they believe that another country has already launched nuclear weapons towards the US.

Although legally the president could invoke this ability in any situation, and just launch nuclear weapons on a whim because they are angry or having a bad day or whatever, they would surely be ignored if they tried to invoke this ability to launch within four minutes in peacetime. Legally that would be mutiny, but those who refused to obey the orders could argue that their president is deranged and unfit to serve, and at any rate in such circumstances nobody would be likely to challenge the refusal to obey his or her commands except the president him or herself. It would probably lead swiftly to impeachment.

I wrote this for my new blog "Debunking Doomsday" on Quora. I get so many pm's and comments about doomsday stories and it would overwhelm this blog to post articles debunking all the stories you get every week here. So I've started a new blog, and you can tell how many questions I get in this topic area, as nearly all the posts there so far are for questions I've been asked since yesterday. See Debunking Doomsday.

Anyway I thought this particular one was worth republishing here especially as it is very topical with the exchange between Donald Trump and Hilary Clinton on nuclear weapons in the third debate. So here it is, original is at: Debunking: a president of the US could order a nuclear attack at a moments notice on a whim

IN DETAIL

First to be scared of nuclear war certainly is a rational fear. It’s not a hoax or an absurd idea like most of the ones I debunk. I had some fear of nuclear weapons during the cold war. Including nightmares that we’d been hit by nuclear weapons. I’m sure many did back then.

Not so much now, because I don’t feel that an all out nuclear war is likely myself. We are much more connected world wide, than before, with internet, and fast communications, satellites etc, and though there are tensions between Russia and the US, also involving China, it’s nothing like what it was during the cold war, seems to me. And everyone has so much to lose in an exchange of nuclear weapons.

Anyway many people are worrying about the US president or Putin starting a nuclear war, particularly the US president as a result of the short exchange on nuclear weapons between Hillary Clinton and Donald Trump in the third debate.

Many people in these online debates talk about a two person rule. But no, that doesn't apply to the president. I'm using as my sources here the NY Times article: Debate Over Trump’s Fitness Raises Issue of Checks on Nuclear Power. and the Politico article by Bruce Blair , a nuclear security expert: What Exactly Would It Mean to Have Trump’s Finger on the Nuclear Button

It says that a president can order a nuclear attack all by himself or herself in theory, as the two person rule only applies to missile silos and submarines. The defense secretary doesn’t have to approve it, as he or she is second in chain of command to the president who makes the order.

"The NCA consists only of thePresident and the Secretary of Defense or their duly deputized alternates orsuccessors. The chain of command runs from the President to the Secretary ofDefense and through the Joint Chiefs of Staff to the Commanders of the Unified andSpecified Commands."

World-Wide Military Command and Control System, DoD Directive S-5100.30

But in practice a president who ordered a nuclear attack in peacetime might well face some kind of a mutinous action, refusal to follow his orders, moves to be declared unfit to govern etc.

This actually happened to president Nixon, not that he ordered an attack, but that towards the end of his presidency they no longer trusted him with the nuclear button, because of drink problems etc. So, though it was not legal for them to do it and probably mutinous considered from a legal point of view, the secretary of defense James R. Schlesinger instructed the military to divert all emergency orders especially any involving nuclear weapons, to him. In the circumstances nobody was likely to challenge this.

There’s a difference here between a decision to do a first strike, and a response to an attack. After being told about an attack, the president may have only minutes to decide whether to treat it as a false alarm or to respond, and what response to take.

That’s what Hillary Clinton is talking about here in the third debate, six minutes into this extract.

It’s confusing because she pivots. She starts by talking about Trump’s idea of a unilateral nuclear attack in peacetime. But the end of her sentence when she talks about the 4 minutes and saying that former presidents say Trump is not a suitable person to respond in a situation like that she is talking about response if you hear that there has been a nuclear attack on the US. Is it a false alarm? Do you get on the phone to Putin or to China or N. Korea or whoever? Or do you just respond right away.

She is saying at that point that he is not a fit person to make such a decision.

But she isn’t saying that a president in peace time can launch a nuclear attack with only 4 minutes of warning for no reason. If a president did that I’m sure they would be treated as temporarily insane, of diminished responsibility, and ignored. Whether it is Clinton or Trump or whoever it is.

But because of the pivot it’s not so clear, she is somewhat giving the impression that Trump would be able to launch a nuclear weapon in peacetime within 4 minutes.

If challenged I’m sure she’d deny that is what she meant. It’s the sort of thing politicians often do in debate to score a point, pivoting like that.

Incidentally I think it is totally immoral to launch nuclear weapons at all and if someone has dropped a nuclear weapon on your state, heaven forbid as they say, then it does not make it acceptable to use them. Jeremy Corbyn, leader of the opposition in the UK, and long term opponent to nuclear weapons has said that if he is prime minister he will never give the order to launch nuclear weapons. Theresa May has said unequivocally that she would, if it came to it, the first prime minister to answer this question in the affirmative (previous ones have refused to answer). So we have quite a polarity in politics on this matter here in the UK.

Somewhat longer response, added several new sections, in my new blog: Debunking: a president of the US could order a nuclear attack at a moments notice on a whim by Robert Walker on Debunking Doomsday

Also made it into an article on Science20 here: Debunking: A President Of The US Could Order A Nuclear Attack At A Moments Notice On A Whim