Facebook Inc (FB.O) said  it took down posts and ads run by the re-election campaign of U.S. President Donald Trump for violating its policy against organized hate.

The ads showed a red inverted triangle, a symbol the Nazis used to identify political prisoners, with text asking Facebook users to sign a petition against antifa, a loosely organized anti-fascist movement.

Trump and Attorney General William Barr have repeatedly singled out antifa as a major instigator of recent unrest during nationwide anti-racism protests, with little evidence.

A screenshot from Facebook’s ad library shows an ad run by Republican President Donald Trump’s campaign, one of many using the same symbol that Facebook took down on Thursday for violating its policy against organized hate.

The symbol was in Facebook ads run on pages belonging to Trump and Vice President Mike Pence, as well as on ads and organic posts on the “Team Trump” page.

He also said that there have been some antifa who have used the red triangle, but that it was not a particularly common symbol used by the group.

A red triangle that marked ‘political prisoners’ was the most common category of prisoners registered at the German Nazi #Auschwitz camp.

In August 1944, political prisoners constituted 95 percent of camp prisoners’. A letter inside the triangle could mark the nationality.