Illustration by Tom Bachtell

It’s often said of the Trump era that the Republic has drifted into uncharted waters, but the more damning estimation is that we are mindlessly revisiting some of the darker regions of our historical map. A century ago, President Woodrow Wilson committed American forces to what was then known as the Great War. The monstrous scale of the battle, coinciding with a rise in the number of immigrants; the mass migration of African-Americans from the South to the North, in pursuit of employment; and the shock of the October Revolution, in Russia, all served to create an atmosphere of tension and suspicion in the United States. The government responded with a crackdown on what it loosely termed “sedition.”

The newly formed Federal Bureau of Investigation obsessed over all manner of “radicals,” but particularly those African-Americans whose meekest protests of racism were regarded as subversion. African-American newspapers that reported on lynchings were deemed destructive to wartime morale, and the Post Office threatened seizure of subscription copies. This narrowing of free expression had wide-ranging implications, especially for civil-rights organizations and activists.

A 1919 document titled “Final Report on Negro Subversion,” which came to the desk of a twenty-four-year-old Justice Department staffer named J. Edgar Hoover, portrayed the civil-rights movement as potentially Bolshevik-inspired, and suggested that black discontent might easily turn into support for Communism. At the same time, the Ku Klux Klan, which had been all but crushed by a series of anti-terrorism laws passed during Reconstruction, surged back to life after the release, in 1915, of the film “Birth of a Nation.” Yet its transformation from a Southern phenomenon into a national one elicited little concern from law-enforcement officials, some of whom were members.

The nativist inclinations of the Trump Administration recall fraught moments of this past. So perhaps it is no surprise that the Hoover-era view of African-American radicalism resurfaced a week ago, when Attorney General Jeff Sessions appeared before the House Judiciary Committee. Sessions was on Capitol Hill to answer questions about his knowledge of any contacts the Trump campaign may have had with representatives of the Russian government, but he was also asked about an F.B.I. report titled “Black Identity Extremists Likely Motivated to Target Law Enforcement Officers.”

The report, which was issued in August and leaked to ForeignPolicy.com last month, argues that the increased scrutiny of police shootings of African-Americans in recent years may result in acts of violence directed at law enforcement. It cites a 2014 incident, in which a man attacked four N.Y.P.D. officers with a hatchet, and a 2016 attack on police in Baton Rouge that left three officers dead. But the primary example is the shooting during an anti-police-brutality rally in Dallas last year, when Micah Xavier Johnson, a twenty-five-year-old Army veteran who harbored resentment toward whites, in general, and toward white law-enforcement officials, in particular, killed five policemen and wounded seven more, before he himself was killed.

In discussing such incidents, the report coins the category “black-identity extremist,” which is poorly defined but features the three-word rhythm of other usefully ambiguous terms, such as “radical Islamic terrorist.” The authors argue that people sympathetic to the Sovereign Citizens movement and to the Moorish Science Temple of America, both of which reject the authority of the federal government, warrant vigilance, even though violence conducted by any such sympathizers “has been rare over the past twenty years.” In an effort to ground their conclusions in history, the authors point to radical organizations of the nineteen-seventies, such as the Black Liberation Army, which has been defunct for longer than Johnson had been alive, and for which they offer scant connection to the B.I.E. cause.

When Representative Karen Bass, of California, asked Sessions about the report, he said that he had not yet read it but he nonetheless stood by its findings. When she pressed him to cite an organization committed to the kind of violence the report warns of, he said, “There are groups that do have an extraordinary commitment to their racial identity and some have transformed themselves even into violent activists,” but declined to name any. The black-identity extremist appears to be something of a bureaucratic phantom, yet that kind can be the most difficult to exorcise. The “Final Report on Negro Subversion” prefaced a long engagement between the F.B.I. and organizations seeking to realize black rights, which included the surveillance of Martin Luther King, Jr., as well as the Bureau’s COINTELPRO efforts to destroy the Black Panther Party. When James Comey was the Bureau’s director, he kept on his desk a copy of the approval of Hoover’s request to wiretap King, as a reminder of the perils of organizational excess.

The killing of the five Dallas police officers—Lorne Ahrens, Michael Smith, Michael Krol, Patrick Zamarripa, and Brent Thompson—was a tragedy. But Johnson was a troubled, isolated individual with no known allegiance to any terrorist organization. Since 9/11, far-right extremists have been responsible for more attacks in the United States than terrorists acting in the name of any other cause. Yet, when Representative Bass asked Sessions if the Bureau had issued any similar report about white-identity extremists, he replied, “I’m not aware of that.”

In next month’s U.S. Senate election in Alabama, voters will choose between Doug Jones, who, as a U.S. Attorney, prosecuted two Klan members for their involvement in the 1963 bombing of the Sixteenth Street Baptist Church, in Birmingham, which killed four African-American girls, and Roy Moore, who, after being removed from the State Supreme Court, fought against the removal of provisions for racially segregated education in the state constitution. Nothing dead is buried, and what we thought was dead lives on. If the redundancy of this history offers any lesson, it’s how easy it is for concern about a vaguely defined enemy to translate into the suppression of rights—and that the targeting of marginalized groups is often the first indication that such a process is under way. ♦