(5) the term "domestic terrorism" means activities that--
(A) involve acts dangerous to human life that are a violation of the criminal laws of the United States or of any State;
(B) appear to be intended--
(i) to intimidate or coerce a civilian population;
(ii) to influence the policy of a government by intimidation or coercion; or
(iii) to affect the conduct of a government by mass destruction, assassination, or kidnapping; and
(C) occur primarily within the territorial jurisdiction of the United States.
Looking at the offenses though, might be tough to get a prosecution for supporting domestic terrorism. Still, I'd keep a bookmark on this section of the criminal code. Antifa is at least a potential violator.
I am not going to expect the FBI to step up and do anything about it. Their former leader has been exposed to be useless and dishonest.
[(i) to intimidate or coerce a civilian population;
(ii) to influence the policy of a government by intimidation or coercion]
I’d say it’s right there.