I first heard about “Antifa” in 2017. And I heard it didn’t exist; it was merely a descriptor. If you were opposed to fascism, you might describe yourself as “anti-fa” or antifascist. And I know a lot of such people.
Living in Baltimore, I have come across communists, greens, labor groups, and various activist groups with far left ties and historic KGB connections. Other groups have China connections.
They were always obvious to me and I knew which individuals were involved in specific groups. I never knew of anyone involved in “antifa,” never saw a meeting of such a group, never saw a poster promoting it.
The Trump administration is literally trying to manifest an enemy out of thin air in order to criminalize its opponents. This is obviously incredibly dangerous, a red flag for rising authoritarianism, and a gestapo tactic for justifying the use of force by the state.
Dave Troy 
Mike Fraser