I don’t think I used the term ‘domestic terrorists’ ... these bastards are international.
Antifa is an old communist terror group, with lots of ups and downs in their history. Back in the days they worked with the Baader-Meinhof gang they were designated a terror organization by several European countries. Personally, I see a consistent history back to their birth as the Communist militia under the Weimer Republic in 1932. However they are different groups using different. Like the post Civil War KKK, the early 20th century KKK and some would see the post WWII KKK as a third organization. All with the same ideology. I'm not sure a single Antifa organization exists in the US, rather kindred groups. Like the many Arab terror groups on the State Dept list. I don't know there's an easy link to non US groups. Though I wouldn't care if State designated them, assuming they could make it stick.