John Hinderaker calls it out clearly in this article. I can only add a few additional supportive points of my own.

Hong Kong’s political conflict took a sinister new turn last night when masked Triad gangsters burst into underground train carriages and used sticks to beat up passengers after the latest anti-government protests.

Film posted on social media showed men in white T-shirts and black shorts lashing out indiscriminately at screaming passengers as they ascended a crowded escalator at Yuen Long station, close to Hong Kong’s crossing point to mainland China.

The assumption of many people in Hong Kong, however, will be that the thugs were hired, perhaps not directly by the authorities, but with the tacit approval of people in power in Hong Kong or Beijing.

The same thing is happening in Venezuela, where the Maduro regime uses privately-organized death squads to attack the regime’s opponents. And it is happening in Portland, Oregon, where the fascist Antifa gang attacks passers-by with impunity while police do little or nothing. So far, Democratic Party politicians have seemed to enjoy having their thugs smashing store fronts, setting buildings and vehicles on fire, and attacking others with bats, two-by-fours and iron bars. Condemnations of Antifa have been few and far between, while prominent Democrats like Keith Ellison, a former Congressman, Deputy Chairman of the Democratic National Committee, and now Attorney General of Minnesota, have promoted the organization.

Antifa, the new KKK, or military wing of the Democratic Party.

A political cartoon depicting the KKK and the Democratic Party as continuations of the Confederacy

And it happened in Fascist Italy and Germany, in nearly the same way.  In Germany, the quasi official private political army of thugs wore brown shirts as a kind of uniform - the only difference in Portland is they wear black, in Communist China it's white - and were formally known as "brown shirts."  The Sturmabteilung.

Is it not richly ironic that all the Portland Antifa, who want to "punch a Nazi," and practice violence against their political enemies, are virtually identical in their behavior to the actual Nazi's?

Hiring bands of lawless thugs to physically attack those with whom they disagree and to force those same people out of the political arena is the act of totalitarian ideologies across time and around the world, which reject the rule of law and the legitimacy of elections.  The use of violence to gain political power is deeply undemocratic and at odds with every point of our founding ideology as set forth in the Constitution and Bill of Rights.  As such, Antifa and any similar violence based organization is profoundly un-American.

They are political terrorists, and should be treated accordingly.

Interesting factoid: Brown-colored shirts were chosen as the Sturmabteilung uniform because a large number of them were cheaply available after World War I, having originally been ordered during the war for colonial troops posted to Germany's former African colonies.