The United States could see an increase in violent extremism in 2017 – but not because of Muslim extremism.

The September 11 attacks were a "black swan," a high-impact, low-probability event that is almost impossible to see coming. One of the 9/11 Commission's conclusions was that the 2001 attacks succeeded, in part, because of a failure of imagination. Who could have guessed that terrorists would use airplanes as weapons of mass destruction in a suicidal attack? No one, evidently.

Since then, U.S. homeland security efforts have attempted to imagine it all, from biological attacks in subways to EMP attacks on the electric grid (neither of which we're ready for, by the way). Yet, I fret we have slipped into another malaise of imagination. A significant, even outsized portion of law enforcement and counterterrorism efforts are focused on the threat from Muslim extremists. It dominates security policy and American politics. That threat is valid, but in all our angst over the Islamic State group and those it inspires, we may be missing some terrible dark wings flapping over the horizon.

There is plenty of solid reporting and opinion writing on how Republican presidential nominee Donald Trump appears to be parroting white supremacist views and ideas, for reasons debatable. I'm less concerned with whether Trump is a racist and more concerned with the number of racists who believe he is. He is the chosen leader for right-wing extremists, regardless of whether he means to be.

A former Grand Wizard of the Ku Klux Klan likes and supports Trump. Some of the people who show up at his rallies are part of racist right-wing groups. All manner of white supremacists on social media regularly chime in to voice their endorsement, as do users of the widely read white supremacist online forum Stormfront. And on Tuesday, a violent extremist in Olympia, Washington attacked an African-American and his girlfriend outside of a restaurant, citing hatred of the Black Lives Matter movement and, according to court documents, saying he would head over to a Trump rally next to "stomp out" more members of the movement.

As you read this, there are KKK recruitment flyers being distributed around the country, tossed into front lawns, left on sidewalks; they're everywhere, from North Carolina to San Francisco, offering a phone number and an email address, encouraging people to get in touch. This active recruitment is just the latest example of a long-running trend in extremist right-wing recruitment. Just last year, the number of hate groups in the United States rose 14 percent (a portion of which owed to growth in Black Separatist groups), and the number of KKK chapters more than doubled to 190, according to the Southern Poverty Law Center.

Bottom line: There is a growing white supremacist movement in the country that views Trump as an advocate.

So while the political right is vowing to defeat "radical Islamic terrorism," the Islamic State group is committing atrocities and homegrown attacks are occurring in Europe and the United States, we have a fast-growing, highly motivated group of right-wing extremists who are quite openly saying that their day has come.

What happens if Trump wins? What happens if he loses?

We can speculate. If he wins, it gives political and moral top-cover to thousands of people who see non-Anglo-Saxon Protestants as inferior. The fact that Trump is seen as a champion for white supremacy means a political victory is also an ideological victory in the eyes of his supporters. A Trump win in November, in part, legitimizes the supremacist argument, which can only lead to conflict and violence.

And if Trump loses, are all these people going to praise democracy and accept that they just didn't get out the vote? The Republican candidate has already said that if he loses in Pennsylvania it will be because of cheating. And his political failure will indicate to at least some white supremacists that where democracy fails them, perhaps violence will not.