How can an organisation that is not an organisation by any measure of the word, be considered an internal terrorist threat? Unless you simply need to broad stroke your enemies and remind them that disagreement will alight at a cost.
ANTIFA simply means anti-fascist, and encompasses all elements of societal structure’s that oppose Trump, and who rightly contend that he is an actual fascist dictator.
Trump has already abandoned the constitution by ignoring court orders, disassembling institutions nearly 250 years old just so he can turn the American economy into a ponsy scheme that benefits his own family, while instituting illegal executive orders as he literally murders people on the high seas, while ignoring civil rights in blue states.
The Theocratic States already exist.
Trump will never surrender power, ergo the constitution is dead, and America is now a fascist state.