FILE PHOTO: U.S. President Donald Trump signs an executive order in the Oval Office at the White House in Washington, D.C., U.S., September 19, 2025. REUTERS/Ken Cedeno/File Photo

By Trevor Hunnicutt and Jana Winter

WASHINGTON (Reuters) -U.S. President Donald Trump will sign an executive order as soon as Monday designating the antifa movement a "terrorist organization," the White House said, after promising actions targeting left-wing groups following Charlie Kirk's assassination.

Kirk, a prominent conservative activist with close ties to Trump, was assassinated on September 10 while speaking on a college campus in Utah. A 22-year-old technical college student has been charged with Kirk's murder.

Investigators are still looking for a motive and have not said the suspect operated in concert with any groups. But the Trump administration has used the killing as a pretext to revive years-old plans to target left-wing groups they regard as being hostile to conservative views.

Antifa, short for anti-fascist, is a "decentralized, leaderless movement composed of loose collections of groups, networks and individuals," according to the Anti-Defamation League, which tracks extremists.

"While some extreme actors who claim to be affiliated with antifa do engage in violence or vandalism at rallies and events, this is not the norm," it says on its website.

A Justice Department official with knowledge of discussions on the issue said the designation of antifa as a terrorist group would unlock expansive investigative and surveillance authorities and powers.

The person, who declined to be named, said the designation would allow the U.S. government to more closely track the finances and movements of U.S. citizens and to investigate any foreign ties of the loose network of groups and non-profits the Trump administration views as antifa.

FOCUS IS ON FOREIGN FUNDING

Critics of the administration have warned that it may pursue an attack on free speech and opponents of the Republican president.

The FBI's Counterterrorism and Counterintelligence Divisions will be used to track finances - both domestic and foreign sources of funding - and attempt to identify the central leadership of antifa, the official said. FBI surveillance and investigative operations are normally restricted in how they can target U.S. citizens.

"The big picture focus is on foreign money seeding U.S. politics and drawing connections to foreign bank accounts," a White House source familiar with the plans told Reuters.

"The designation of antifa gives us the authority to subpoena banks, look at wire transfers, foreign and domestic sources of funding, that kind of thing," the White House source said.

Political violence experts and U.S. law enforcement officials have previously identified far-right attacks as the leading source of domestic violent extremism. Trump administration officials have sought to portray left-wing groups as the main drivers of political violence in their remarks since Kirk's death.

"Antifa is going to be designated a domestic terrorist organization," said White House spokeswoman Karoline Leavitt at a press briefing. "The president intends to sign that executive order very soon, as soon as it's drafted, as soon as today."

The precise legal authority Trump's order would draw on was not immediately clear, nor was its effect. The U.S. government does not currently officially designate solely domestic groups as terrorist organizations in large part because of constitutional protections.

Legal experts have said such steps may be legally and constitutionally dubious, hard to execute and raise free-speech concerns, given that subscription to an ideology is not generally considered criminal under U.S. law.

During the first Trump administration there were at least two failed efforts to designate antifa a terrorist organization, according to internal Department of Homeland Security communications viewed by Reuters.

(Reporting by Jeff Mason, Trevor Hunnicutt and Jana Winter; Editing by Ross Colvin, Chris Reese and Marguerita Choy)