Anyone funding the group should be investigated, the president said.
Antifa will be designated by the United States as a terrorist organization, President Donald Trump announced after midnight on Sept. 18 while visiting the United Kingdom.
โI am pleased to inform our many U.S.A. Patriots that I am designating ANTIFA, A SICK, DANGEROUS, RADICAL LEFT DISASTER, AS A MAJOR TERRORIST ORGANIZATION,โ Trump posted on Truth Social.
The president said he would also strongly recommend that anyone funding the group be investigated.
Trumpโs announcement was made after he and the first lady met with Britainโs royal family at Windsor Castle on the first day of a two-day state visit to the UK.
On Monday, Trump hinted at the designation, saying he would support it in the wake of the assassination of Christian conservative commentator Charlie Kirk last week.
โItโs something I would do, yeah, if I have the support from the people back here,โ Trump said, referring to administration officials standing behind him, including Attorney General Pam Bondi.
โAntifa is terrible,โ Trump added.
Antifa gathered outside the castle in London, chanting, โCharlieโs in a boxโ on Wednesday, referring to Kirk.
โThese societal outcasts are so removed from reality they think itโs funny to laugh at patriots being horrifically murdered,โ Turning Point UK, a branch of Kirkโs organization Turning Point USA, posted on X.
ANTIFA chant โCharlieโs in a boxโ at anti-Trump London protest.
— Turning Point UK ๐ฌ๐ง (@TPointUK) September 17, 2025
These societal outcasts are so removed from reality they think itโs funny to laugh at patriots being horrifically murdered.
Itโs not about left vs right anymore itโs about good vs evil.@NewsNowYorks pic.twitter.com/MOJiEw4pl2
The suspect in Kirkโs assassination, Tyler Robinson, is believed to hold extreme leftist viewpoints, according to officials. He also engraved anti-fascist messages on bullets that were recovered by officials.
The FBI continues to investigate the assassination but has not said whether Robinson was in communication with or associated with any antifa groups.
Antifa was initially part of the Soviet Unionโs front operations to bring about communist dictatorship in Germany, and it worked to label all rival parties as โfascist.โ
The organization can be traced to the โunited frontโ of the Soviet Unionโs Communist International (Comintern) duringย the Third World Congress in Moscow in June and July 1921, according to the German booklet โ80 Years of Anti-Fascist Actionโ by Bernd Langer, published by the Association for the Promotion of Anti-Fascist Culture. Langer is a former member of the Autonome Antifa, formerly one of Germanyโs largest Antifa organizations, which disbanded in 2004.