WASHINGTON >> The Justice Department is establishing a specialized unit focused on domestic terrorism, the department’s top national security official told lawmakers today as he described an “elevated” threat from violent extremists in the United States.

Assistant Attorney General Matthew Olsen, testifying just days after the nation observed the one-year anniversary of the violent insurrection at the U.S. Capitol, said the number of FBI investigations into suspected domestic violent extremists has more than doubled since the spring of 2020.

“We have seen a growing threat from those who are motivated by racial animus, as well as those who ascribe to extremist anti-government and anti-authority ideologies,” Olsen said.

Olsen’s assessment tracked with a warning last March from FBI Director Christopher Wray, who testified that the threat was “metastasizing.” Jill Sanborn, the executive assistant director in charge of the FBI’s national security branch who testified alongside Olsen, said today the greatest threat comes from lone extremists who radicalize online and look to carry out violence at so-called “soft targets.”

The department’s National Security Division, which Olsen leads, has a counterterrorism section. But Olsen told the Senate Judiciary Committee that he has decided to create a specialized domestic terrorism unit “to augment our existing approach” and to “ensure that these cases are properly handled and effectively coordinated” across the country.

The formulation of a new unit underscores the extent to which domestic violence extremism, which for years after the Sept. 11 attacks was overshadowed by the threat of international terrorism, has attracted urgent attention inside the federal government.

But the issue remains politically freighted, in part because the absence of a federal domestic terrorism statute has created ambiguities as to precisely what sort of violence meets that definition.

Several Republican senators, for instance, suggested today that the FBI and the Justice Department had given more attention to the Jan. 6 insurrection than to the 2020 rioting that erupted in American cities and grew out of racial justice protests.

Republican Sen. Ted Cruz of Texas accused the department of “wildly disparate” treatment. Sen. Chuck Grassley of Iowa, the Senate’s top Republican, played video clips of the 2020 violence as a counter to the video of the Jan. 6 Capitol rioting played by Democratic Sen. Richard Durbin, the committee’s chairman.

The officials said the department treats domestic extremist violence the same regardless of ideology.