U.S. President Donald Trump has announced plans to designate “Antifa” a loosely organized network of far-left activists  as “a major terrorist organization,” reviving a threat he first made during his presidency.

Writing on Truth Social Wednesday, Trump called Antifa “a sick, dangerous, radical left disaster” and said he would recommend thorough investigations into “those funding ANTIFA” in line with “the highest legal standards.”

For years, Trump has blamed Antifa for violence at protests, attacks on police, and even the January 6 Capitol riot despite widespread evidence that the assault was carried out largely by pro-Trump groups.

Antifa, short for “anti-fascist,” is not a formal organization. A 2020 Congressional Research Service analysis described it as a collection of “independent, radical, like-minded groups and individuals” rather than a national body.

While federal law enforcement monitors domestic extremism, the United States does not maintain a list of designated “domestic terrorist organizations.” In fact, during Trump’s first term, FBI Director Chris Wray told Congress that Antifa was “a movement or an ideology,” not a group that could be formally designated.

Critics warn that labeling Antifa as terrorists could be used as a political weapon to suppress dissent and target rivals. Trump’s renewed threat follows comments by senior adviser Stephen Miller, who vowed the administration would dismantle what he called a “vast domestic terror movement” linked to the recent killing of conservative activist Charlie Kirk.

Antifa’s origins trace back to socialist groups in 1930s Germany that resisted Hitler. In the U.S., Antifa activists, often dressed in black, have confronted far-right demonstrators and engaged in disruptive tactics they describe as “self-defense.” The movement gained prominence during Trump’s first inauguration in 2017, the Charlottesville clashes later that year, and protests following George Floyd’s death in 2020.

As of Wednesday, Antifa is not listed among the 95 foreign terrorist organizations on the State Department’s official registry.