FBI agents have disrupted and stopped what they say was a conspiracy by militia movement members to kidnap Michigan Gov. Gretchen Whitmer, a Democrat. They discussed arson of her vacation home and other targets and kidnapping her for "trial."

This isn't just a one-off event or the work of a few mad actors — it's part of a rising tide of white power activity, one that poses an imminent danger to American democracy. The Department of Homeland Security's threat assessment report, released earlier this week after a long wait, made that clear: White power movement violence and affiliated extremism is, by far, the greatest terrorist threat to our nation.

Not only does this kind of extremist violence outstrip any violence carried out by what President Donald Trump has referred to as "antifa and the left," but white power violence now also exceeds the threat of radical Islamist terror. The DHS assessment makes clear that "2019 was the most lethal year for extremism in the United States since the Oklahoma City bombing in 1995."

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That bombing, the largest deliberate mass casualty on mainland American soil between Pearl Harbor and 9/11, is still not well understood by Americans. People still think of it as the work of lone wolves or a few bad apples. But the Oklahoma City bombing, which killed 168 people — including 19 young children — was the work of the white power movement, a coordinated social network that brought together Klansmen, neo-Nazis, skinheads, militiamen, radical tax resisters, separatists and others in outright war on the federal government. The evidence of the bombing as part of this movement is extensive and irrefutable.

And it presaged the problem we face now. Twenty-five years later, the threat of white power domestic terrorism is inescapable. Experts agree. Watchdogs agree. Whistleblowers agree. Deradicalizers agree. Scholars agree. Everyone, it seems, but the upper echelons of the Trump administration, and the most unreachable corners of his base, agree: White power violence has been unleashed.

I studied the earlier white power movement for more than a decade. Now, I'm very concerned that more violence is imminent, and that these ideologies pose a threat to our democracy and to people going about their everyday lives.

The evidence is there, but it's easy to overlook if you don't connect the various alarming details. The attempted kidnapping of Whitmer is linked to the call to arms of the Proud Boys, the underground training of other white power groups, the militias and "boogaloo boys" on the march and the string of mass shooters motivated by this ideology.

In the new Michigan case, the FBI's transcripts reveal a highly volatile set of plots that included bombings of multiple targets and a coded reference to attempted murder. In white power discourse, kidnapping people for "trial" is often followed by references to lynching. Whitmer might easily have been assassinated by this group.

But again, seeing incidents like this as one-off cases obscures how deep this threat is. So here's just a partial list of violence white power activists have caused or attempted since the early 1980s:

Detonating a nuclear power plant as a bomb. Poisoning the public water supply of a major city with hundreds of gallons of cyanide. Stealing military weapons (including antitank weapons) from military posts and armories.

Assassination of political opponents. Assassination of state troopers, federal judges, people who make multicultural television shows, a radio hosts and FBI agents. Murder of unfaithful women. Murder of people in interracial relationships. Trial and hanging of elected officials, journalists, communists and "racial enemies."

Attempts to steal surface-to-air missiles. Establishment of a cell-style terrorist network. Use of the early Internet to post assassination lists. Theft of land mines from military armories.

Establishment and routine use of paramilitary training camps. Training in urban warfare. Training in field medicine, with a focus on post-atomic survival. Training in killing, using targets with caricatures of racial enemies.

Bombing of gas lines. Bombing of the Hoover Dam. Bombing of bridges. Bombing of synagogues. Bombing of an ethnic studies classroom. Bombing of the Oklahoma City federal building.

On top of these decades of organizing, we now encounter a new urgency among white power activists, who have capitalized upon the Trump administration's many green lights, the anti-mask movement and the social anxieties of pandemic and racial justice protest to launch new campaigns of violence.

This is a movement expressly dedicated to the violent overthrow of the United States and the destruction of democracy and its institutions. We have to stand against it. Read, vote, spread the word. Keep each other safe.

Kathleen Belew is author of "Bring the War Home: The White Power Movement and Paramilitary America" and is assistant professor of history at the University of Chicago.