In the history of political thought there have been many rationales offered for democracy as an ideal of self-government, just as there have been many criticisms of the very idea of democracy.

One of the most cogent rationales is the simple idea that regular democratic elections make political power accountable, because they require elected politicians to be responsive to electorates if they wish to remain in office, and because they make it possible to remedy bad public policies by “throwing the bums out” in the next election. This view is sometimes described as “realist,” since it makes no grand assumptions about the rationality of ordinary citizens, and it is sometimes described as “minimalist,” since it posits no great values to be served beyond simple electoral accountability. On this view, while democracy promises no great public edification or enlightenment, it does promise that citizens can at least remedy the worst errors committed by those who govern in their name. They can do so because whatever is done in the citizenry’s name at a given point in time, at some predictable future point in time, that thing can be reevaluated and potentially reversed by electing politicians committed to something else.

Yesterday Donald Trump declared that North Korea’s development of a nuclear ICBM was intolerable, and that: “North Korea best not make any more threats to the United States. They will be met with fire and fury like the world has never seen… he has been very threatening beyond a normal state. They will be met with fire, fury and frankly power the likes of which this world has never seen before.”

Donald Trump is no ordinary individual. For on November 8, 2016, he was elected the 45th President of the United States. It is true, and worth mentioning, that due to the rather arcane and anachronistic rules governing U.S. Presidential elections, he won this election in the Electoral College, despite having received 3 million popular votes less than his opponent, Hillary Clinton. It is also worth mentioning that this election involved apparent Russian interference that is now the subject of House and Senate investigations and also the subject of a Justice Department investigation being led by Special Counselor Robert Mueller. Trump is President nonetheless. And yesterday’s chilling words raise fundamental questions of war and peace, political ethics in the nuclear age, and democratic legitimacy itself.

The Trump administration has put democratic theory to the test in many ways. While we might imagine that a democratically elected President would staff his administration with experienced and qualified individuals, Trump has placed inexperienced family members in important White House positions while failing to fill other important positions. While we might imagine that a democratically elected President would make public policy based on facts, and would communicate public policy to the citizenry in a factually accurate way, Trump disparages expert advice presented to him by qualified governmental officials, preferring to trust right-wing extremist web sites; communicates with the public mainly through early-morning Tweets that say more about his state of mind than about public policy; and manifestly lies about what is happening and what he is doing. While we might assume that a President in a democracy would regard a free press as an important institution, Trump regularly and consistently disparages, denounces, and demonizes the press, declares that all independent media institutions are purveyors of “fake news,” and has gone so far as to set up his own alternative media institutions to propagandize on behalf of his own version of “the truth.” And while we might imagine that the President in a constitutional democracy would be subject to the law, Trump behaves and speaks as if he is entirely above the law.

Trump, in short, governs in a manifestly authoritarian manner. This has been widely noted by journalists and commentators across the political spectrum (including prominent Republicans such as Joe Scarborough and George Will), and it has resulted in the emergence of significant “resistance” movements seeking to counter his actions and to lay the groundwork for electoral challenges in the Congressional election of 2018 and in the Presidential election of 2020.

It would be true to say that Trump represents a fundamental threat to U.S. constitutional democracy. It could also be said that many of the institutions of this democracy — Congress, the courts, the press, citizen groups — have to at least some extent worked to counter Trump, and to employ the conventional tools of democratic opposition to limit and to repair the damage that he is doing. For the past six months, it has been the premise, and the hope, of a great many people, Democrats, independents, and even Republicans, that democracy will work in this way, however disturbing the statements and actions of this President.

But then there was yesterday. Yesterday Donald Trump threatened the preemptive use of nuclear weapons against North Korea. The words can’t be taken back. They have already produced a dangerous rhetorical escalation. More important, the possible consequences — nuclear war itself — are irreversible.

Virtually every serious expert, including currently serving military officers, has long stated that even a conventional war on the Korean peninsula would be devastating, threatening the lives of many millions of people, including North Koreans, South Koreans, and over 35,000 US troops permanently stationed in South Korea. A nuclear war would be even more devastating. It would threaten both China and Japan, the entire region, and indeed the entire world. A great many commentators and politicians have thus, reasonably, declared that Trump’s statement was “bombastic,” “unwise,” “dangerous,” and even “crazy.” Retired Four-Star General Barry McCaffrey immediately stated on MSNBC that there is “not a chance” that Trump’s statement reflected the advice of his military and national security advisers, because the threat flies in the face of everything that these advisers know. “They’re dealing with a President with an incoherent world view. . . Never in my experience has any President made this kind of a blustering statement . . .” Today’s New York Times confirms McCaffrey, noting in a story bearing the headline “Trump’s threat to North Korea was improvised”: President Trump delivered his “fire and fury threat to North Korea on Tuesday with arms folded, jaw set and eyes flitting on what appeared to be a single page of talking points set before him on the conference table at his New Jersey golf resort. The piece of paper, as it turned out, was a fact sheet on the opioid crisis he had come to talk about, and his ominous warning to Pyongyang was entirely improvised, according to several people with direct knowledge of what unfolded. In discussions with advisers beforehand, he had not run the specific language by them.” If many very serious people have publicly stated that Trump’s threat was dangerous and ill-advised, former Republic Senator Gordon Humphreys has gone further, stating that it is “crazy,” and that Trump’s “poor judgment, belligerence, vindictiveness and reckless impetuosity constitute an indictment of his mental health.” Humphrey is saying what a great many other serious people have been saying for the past six months and longer: Donald Trump is a narcissistic and unstable man, precisely the kind of person who should not have his finger “on the button.”

And yet here we are. This man has his finger on the button. And he is threatening to use it. Trump is playing nuclear “chicken” with a man, Kim Jong-un, well known for his own murderous narcissism. On MSNBC, Evelyn Farkas, a Deputy Assistant Secretary of Defense in the Obama Administration, echoed many in noting that “President Trump sounds more like a North Korean Leader, unfortunately, than an American leader.” Some have even suggested that Trump exceeds the North Korean dictator in his dangerous bluster. Joshua Keating, for example, writes in Slate that “We need one sane leader in the US-North Korea standoff. Pressure’s on you, Kim Jon-un.”

At this moment every US citizen and indeed every thinking human being must come to terms with three basic facts: (1) the US political system empowers the President to command the military; (2) in the nuclear age, the President and the President alone has his veritable “finger on the nuclear button”; and (3) the current President is an arrogant, impulsive, and unbalanced individual who has long been enthralled by the thought that US foreign policy problems can be solved by nuclear war.

While Trump endangers constitutional democracy in so many ways, it is this power, which threatens the lives of millions, that most glaringly exposes the limits of US constitutional democracy. For while most other decisions can be overturned or remedied by future decisions, the decision to proceed down the slippery slope of nuclear brinkmanship, much less to use nuclear weapons—and the blunt public threat to use them is itself a rhetorical use of them — threatens devastating and irreversible consequences that would render democratic accountability meaningless. This was noted decades ago by Robert Dahl in his 1985 book Controlling Nuclear Weapons: Democracy Versus Guardianship: “We have in fact turned over to a small group of people decisions of incalculable importance to ourselves and mankind, and it is very far from clear how, if at all, we could recapture a control that in fact we have never had.” Dahl’s sentiments have long been understood by many. Some have been fine with the undemocratic consequences of nuclear decision-making. Some have had some faith that broader norms, procedures, and institutional imperatives would play some role in constraining nuclear decisions and keep them broadly subject to a presumed public consensus about the logic of deterrence and importance of avoiding nuclear war itself. Some, such as Jonathan Schell in his 1982 best-seller The Fate of the Earth, have raised the alarm over the extreme threat posed by nuclear weapons to democracy and indeed to life on earth itself. In the mid-1980’s such a sensibility indeed inspired mass movements for “nuclear freeze” and sometimes for “abolition.” Then came the Revolutions of 1989, the fall of Communism in Russia and Eastern Europe, the expansion of NATO, and a widespread faith in a “democratic peace” and “an end to history.” The nuclear question receded, and continued to recede.

And here we are.

A madman is in the White House (indeed, he is as likely to be at one of his private resorts as in the White House itself). He is unmoved by the norms and the laws governing a constitutional democracy. He is unmoved by the advice of national security experts, including “his own generals,” who seem to be more important to him as ornaments than as advisors (Defense Secretary James Mattis has today made statements that sound like reinforcements of Trump’s threat. Trump surely is not alone in his brinkmanship. Senator Lindsey Graham has also uttered similar comments. But Trump alone will decide whether and how to threaten, and whether and when to act on his threats). He has stated publicly on more than one occasion that he “knows more than the generals” about military affairs. His finger is on the trigger. And we, citizens of the US and citizens of the world, are mere subjects of his decision.

The whole world is watching.

What will he do? Is there anything we can do but watch? What will become of constitutional democracy? What will become of us? Bracing questions for a terrifying time.