The Muslim American Society (MAS) is a national organization “founded as the overt arm of the Muslim Brotherhood in the United States,” according to court documents. A 2019 MAS event in Philadelphia featured children calling for violent revolution, stating: “We will chop off their heads, and we will liberate the sorrowful and exalted Al-Aqsa Mosque.” In 2014, the United Arab Emirates designated MAS as a terrorist group.