Terrorism in America remains relatively rare, and white-nationalist terrorism causes only a small fraction of the violent deaths in the United States each year. But these attacks are political acts that tear at the social ties that bind Americans together, cause immense psychological trauma to the communities they target, and inspire further acts of violence. The threat these attacks pose, however, extends beyond the violence itself and the wider pain it causes, to the further mainstreaming of the core white-nationalist idea that citizens of European descent are the only true Americans.

Although jihadists are capable of shocking acts of violence, terror, and mass murder, most notably the 9/11 attacks, Muslims compose about 1 percent of the American population. Despite the fevered dreams of the Islamophobia industry, there was never any possibility that the United States would somehow become governed by Taliban-style Islamic law.

By contrast, white supremacy was the governing philosophy of the United States until 1965, a core belief of most of the men who have occupied the Oval Office. Only since the end of the civil-rights movement has the American government truly attempted to be a state for all of its people. Between the Civil War, the violent overthrow of Reconstruction governments by white Redeemers, the thousands of lynchings of the Jim Crow era, and the lives lost in World War II, no single political idea has been responsible for extinguishing the lives of more Americans than white supremacy. Yet despite its long, violent history in the United States, the population it seeks to radicalize exceeds that of Islamist extremism by a couple hundred million.

The strength of white nationalism’s roots in American history is why it poses a different, and more dangerous, challenge—not just to American lives, but to democracy itself. Those roots are precisely why law enforcement has been slow to respond to the challenge posed by far-right terrorism, why most Americans have failed to recognize that such attacks dwarf the number executed by jihadists, and why the Trump administration itself has deliberately chosen to refocus resources elsewhere.

Democrats have proposed specifically criminalizing domestic terrorism under federal law. Any substantial changes to the criminal code should take care not to repeat the worst excesses of the War on Terror, or to criminalize radical speech. (If history is any guide, such speech restrictions would end up being borne not by white nationalists but by the communities targeted by them.)

White nationalism cannot be destroyed simply by imitating ill-advised policies adopted by the United States in an effort to defeat Islamist extremism, such as eliminating due process in the use of lethal force or imprisonment, disregarding protections against illegal search and seizure, criminalizing radical beliefs, or using torture in interrogation. In fact, all of those things would likely make the problem worse. Law-enforcement agencies cannot settle the existential arguments about the nature of American democracy, and it should not be their responsibility to do so.