CNN  — 

President Donald Trump’s threat to label anti-fascism protest movement Antifa a terrorist organization has prompted a backlash in Germany, where thousands of social media users have pledged solidarity with the group.

Trump tweeted on Saturday that the activist group was made up of “gutless Radical Left Wack Jobs who go around hitting (only non-fighters) people over the heads with baseball bats.” He said a move was being considered to label the movement a “major Organization of Terror (along with MS-13 & others),” referring to the international criminal gang the Mara Salvatrucha.

His tweet followed the introduction of a resolution by Republican Sens. Ted Cruz and Bill Cassidy, aiming to have the group identified as “domestic terrorists.”

But the call prompted a flurry of tweets in the US and in Germany, where #IchBinAntifa – I am Antifa – started trending on Twitter.

Several users who used the hashtag referenced Germany’s history of fascism and anti-fascist resistance during the Nazi period.

“#IchbinAntifa because my grandfather fought the fascists after they nearly wiped out our entire family,” Krsto Lazarević wrote.

Another user added, in a tweet that was retweeted hundreds of times: “#IchbinAntifa Because history teaches us just how fragile democracy and the rule of law are when giving right-wing extremists power.”

German daily newspaper Neues Deutschland added that they were “outraged” that Trump was considering labeling the group terrorists.

Antifa, whose name is short for “anti-fascist,” have become increasingly visible since the Charlottesville protests in 2017, when white nationalists rallied against the removal of a Gen. Robert E. Lee statue, and the Antifa mounted a counter-demonstration that turned violent. Trump infamously said in the aftermath that there were “very fine people” on both sides.

The term is used to define a broad group of people whose political beliefs lean toward the left – often the far left – but do not conform with the Democratic Party platform.

The group doesn’t have an official leader or headquarters, although groups in certain states hold regular meetings.

It is known for causing damage to property during protests, and caused controversy when conservative journalist Andy Ngo claimed he had been attacked by members of the movement.

CNN’s Jessica Suerth and Leah Asmelash contributed reporting.