President Donald Trump announced via Truth Social the designation of Antifa as a "major terrorist organization," calling it "A SICK, DANGEROUS, RADICAL LEFT DISASTER" and urging investigations into those who fund it. The declaration comes after the recent killing of conservative activist Charlie Kirk; Trump said he would seek to hold not just those directly responsible, but also those funding or supporting political violence accountable. Legal experts argue that Antifa is not a formal organization but a loosely organized ideology or movement without centralized leadership, making it difficult under U.S. law to apply a "terrorist organization" label domestically. There is no existing legal mechanism equivalent to the Department of State's foreign terrorist organization list for designating domestic groups as terrorists; efforts to do so may raise constitutional issues, including free speech, due process and defining membership in a decentralized entity.