The FBI identifies four categories of domestic terrorists: left-wing extremists, who promote revolutionary movements and the protection of people from capitalism and imperialism in the U.S.; right-wing extremists, who support racial supremacy and anti-government beliefs; single issue groups, who target their attacks against individuals or institutions linked with political issues, such as abortion, testing on animals, and environmental protection; and homegrown Islamic extremists, or U.S. citizens who have become Islamic
