During the final presidential debate on Wednesday night, moderator Chris Wallace asked Donald Trump about his constant assertions that Hillary Clinton is rigging the election. In America, there is a tradition of a "peaceful transition of power, and that no matter how hard-fought a campaign is, that at the end of the campaign, the loser concedes to the winner," Wallace said. "Are you saying you're not prepared now to commit to that principle?"

"What I'm saying is that I'll tell you at the time. I'll keep you in suspense," Trump replied. It fit right in with an earlier comment that Clinton should not have been allowed to run in the first place.

For even a passing student of history, the meaning of this is plain: Trump is toying with the idea of attempting to overthrow the American state by force. It's a stunningly irresponsible thing for a presidential candidate to say. And while such a possibility is a long shot, the U.S. military should probably make some preparations to defend the American state against armed sedition.

A democracy is a system by which the control of the state is awarded via an election. The easy and visibly legitimate process to transfer power is one of the great advantages of such a system. Instead of some Byzantine jostling among whatever heirs some inbred monarch happens to produce, which ends in "bigger army diplomacy" about half the time, you have an election and whoever gets the most votes gets to govern.

But critically, such a system depends on broadly accepted democratic norms throughout both the general population and the elite class. If the electoral system is not accepted as legitimate, or the political results of the election are resisted fiercely enough by a big enough slice of the population, the result is often violence. Stealing an election, as happened in Iran in 2009, almost always leaves an obvious paper trail. Resulting mass protests can easily turn violent, or be suppressed by violence.

Going up the scale of political violence, disgruntled factions can flee to remote areas and attempt guerrilla war. Colombia, for example, has seen a brushfire civil war between leftist guerrillas on one side and the government and right-wing paramilitaries on the other, for the last five decades. Worst of all is organized civil war. The election of Abraham Lincoln to the presidency in 1860, for example, inspired such a fury to protect and expand slavery among Southern conservatives that they broke the country in half for a time and made open war upon the legitimate United States government.

I spell all this out to drive home the immense potential danger of Trump's comments. His assertions about election fraud and Clinton's supposed criminality are either conspiracy derp or outright fabrications, obviously a psychological defense mechanism to avoid having to admit loss. In the 2012 election, he also claimed that the election was a "total sham," that "we should march on Washington" and "have a revolution." Who can say what the 40-60 million Trump voters might do if he tries to incite rebellion? The federal government must prepare for worst.

Of course, it seems all but certain that Trump will not actually retreat to the mountains of West Virginia and start arming insurgents for a campaign against Washington. But the democratic institutions of the United States are already visibly rickety. Trump's conspiracy-mongering will only erode them further. Literally every single other U.S.-style presidential democracy has collapsed, and most of those involved the military in some way. The very thought of the armed forces having to involve themselves in politics is only a short step from the generals choosing who will govern.

For the sake of our democracy, let's hope Trump loses by a spectacular, humiliating margin.