President Donald Trump announced Wednesday the designation of the anti-fascist movement Antifa as a “major terrorist organization,” calling it “a dangerous, sick, radical left-wing disaster.”

Trump stated on Truth Social that he was “designating” the movement a terrorist organization. “I will also strongly recommend that those funding Antifa be thoroughly vetted in accordance with the highest legal standards and practices,” Trump wrote.

Trump indicated on his Truth Social account that he will also recommend vetting those funding Antifa “in accordance with the highest legal standards.” The move comes after the September 10 killing of conservative activist Charlie Kirk.

The Republican’s post did not make clear what mechanism Trump would use to make the designation, and Antifa lacks a centralized structure or defined leadership, making it unclear who or what exactly would be targeted.

Trump and senior officials have repeatedly blamed left-wing groups for creating a climate of hostility toward conservatives leading up to Kirk’s killing. Critics say Trump is using Kirk’s killing as a pretext to crack down on his political opponents. Trump initially floated the idea of ??such a designation for Antifa in 2020 amid violent nationwide protests following the police killing of George Floyd in Minneapolis. At the time, legal experts said such a move lacked a legal basis, would be difficult to enforce, and raised free speech concerns given that espousal of an ideology is not typically considered a crime. Stephen Miller, deputy White House chief of staff, said the Trump administration “is going to channel all of the anger we have over the organized campaign that led to this murder into rooting out and dismantling these terrorist networks.” Despite the designation, investigators have not yet provided a motive for Kirk’s killing,with Tyler Robinson as the prime suspect.