“Antifa” branding was embraced by anti-fascist soldiers of WWII. That’s a bit of a while ago now!

My first experience with it was when I learned a couple of decades ago that not all skinheads were nazis and that there were in fact anti-fascist skinhead punks who called themselves “Antifa.” To be honest, some of them openly bragged about beating up nazi skinheads so I suppose there was some violence involved. I wouldn’t be surprised if Trump heard about those folks and they’re the ones he means, even though they don’t totally own the idea of “Antifa.”

From Wikipedia,

The English word antifa is a loanword from the German Antifa, where it is a shortened form of the word antifaschistisch (“anti-fascist”) and a nickname of Antifaschistische Aktion (1932–1933), a short-lived group which inspired the wider antifa movement in Germany.[43][44][45] The German word Antifa first appeared in 1930. The long form antifaschistisch was borrowed from the original Italian anti-Fascisti (“anti-fascists”).[43

…

In 2007, Rose City Antifa, likely the first group to utilize the name antifa, was formed in Portland, Oregon by former ARA members.[81][5][82] Other antifa groups in the United States have other genealogies. In Minneapolis, Minnesota, a group called the Baldies was formed in 1987 with the intent to fight neo-Nazi groups directly.[61] In 2013, the “most radical” chapters of ARA formed the Torch Antifa Network,[83] which has chapters throughout the United States.[84] Other antifa groups are a part of different associations such as NYC Antifa or operate independently.[85]