The announcement was made Tuesday by Matthew Olsen, the head of the department's National Security Division, and comes as the nation faces a constellation of extremist threats on the home front.
With all the talk about domestic terrorism, you might assume there's a law against it. There's not. The storming of the Capitol has again raised the question about whether one is needed.
The bulletin did not cite any specific threat but said that the risk of violence will persist for weeks. It warned that some extremists may be "emboldened" by the Jan. 6 attack on the U.S. Capitol.
Some say it's the precise word to describe the actions of the pro-Trump extremists who stormed the Capitol on Jan. 6. But others warn its use will do more harm than good.
Reading from U.S. regulations, Mayor Muriel Bowser describes terrorism as "the unlawful use of force and violence against persons or property to intimidate or coerce a government."
As a leader of the Patriot Movement, the Republican representative "planned, engaged in, and promoted a total of three armed conflicts of political violence against the United States government."
"We have uncovered evidence ... that the shooter was exploring violent ideologies," the FBI said. A list of organizations found on the gunman's digital media may have indicated potential targets.
NPR's David Greene speaks with former National Security Council senior director Javed Ali, who's among those calling on the government to make fighting homegrown terrorists a priority.
Lawmakers on Capitol Hill are pushing the federal government to detail its plans to fight white supremacy and other far-right extremism. Details are scarce, but here's what we know so far.
Christopher Paul Hasson, a self-proclaimed white nationalist, allegedly wanted to "kill every last person on earth" in a crusade to establish a "white homeland," according to officials.
Potentially deadly letters and packages are rare, and technology makes it easier to track down perpetrators. But they can play a powerful role in further polarizing the country, analysts say.
Michael Hari has made a stunning array of headlines over the years. An alleged co-conspirator said they wanted to scare Muslims "out of the country." No one was injured.
More than a week after the Las Vegas massacre, investigators are still without a motive. "What survivors really need sometimes is to get closure," one psychologist says.
Leslie Allen Merritt, Jr., 21 was arrested at a Wal-Mart outside of Phoenix in connection with 11 recent highway vehicle shootings. Officials say the acts qualify as domestic terrorism.
Terry Loewen, who pleaded guilty to attempting to drive an explosives-laden vehicle and detonate it at an airport in Wichita, Kan., has been sentenced to 20 years in federal prison.
Usaama Rahim, 26, who was shot and killed on Tuesday after he lunged at authorities with a large, military-style knife, had been plotting to attack "boys in blue," according to an affidavit.
Director James Comey says that Elton Simpson had attracted attention as someone who might attend the Prophet Muhammad cartoon contest, but that the bureau had no reason to believe he would attack.
Former President Bill Clinton and Oklahoma Gov. Mary Fallin spoke at a ceremony remembering the April 19, 1995 bombing — the deadliest act of domestic terrorism in U.S. history.
One suspect reportedly killed himself when his home was surrounded by authorities. A 23-year-old woman from Illinois was among three people arrested in connection with the alleged plot.
Dzhokhar Tsarnaev's attorneys are again asking that his trial, now in the jury selection phase, be moved. Lawyers say they have data showing that enough impartial jurors cannot be found in the city.
