Fears about "homegrown violent extremists" are widespread, and the Department of Homeland Security, the FBI, and the National Counterterrorism Center have all drawn attention to the potential threat from Muslim-American extremism.
Charles Kurzman, an expert on Islamic Movements and a professor at the University of North Carolina, Chapel Hill, has looked in detail at every Muslim-American arrested in 2019 for alleged involvement with violent extremism, to find out the facts on the ground.
In total, 24 Muslim-Americans were arrested of allegations of involvement in violent extremism in 2019, per Kurzman's report:
All but two of these were disrupted as a result of undercover operations. In two cases Muslim community members alerted the authorities; in two other cases non-Muslim community members did so. The investigations of other crimes or suspects' own statements on social media accounted for several more arrests, and another six were caught by law enforcement employees posing as extremists.
Nobody died as a result of actions by Muslim-American extremists in 2019; since 9/11, 141 people in the U.S. have died at the hands of Muslim extremists – among more than 290,000 murders committed by all types of offenders in the U.S. over that time period. There has never been an attack in the United States by a Muslim extremist illegally crossing the border with Mexico.
The Global Terrorism Database, maintained by the University of Maryland, stated in a January 2019 report, "Murder and Extremism in the United States in 2018," that Muslim-American violent extremism was less prevalent than right-wing violent extremism in the United States, even though the former has received more emphasis from the FBI, Department of Homeland Security and the National Counterterrorism Center.
Kurzman also studied concerns that the lead time between radicalization and violence is getting shorter – what is referred to as the "flash to bang" period. Like the fuse on a stick of dynamite, the use of social media has shortened the time between initial radicalization and violent action. However, evidence indicates that the duration between "flash" and "bang" have lengthened, not shortened in recent years.
Kurzman states that "based on the available evidence... there has been no crisis in rapid radicalization to violence, and counterterrorism officials should walk back statements suggesting otherwise."
The evidence shows one reason why this is so: Law enforcement has gotten better and quicker at identifying suspects, thanks in part to a 44 percent increase in undercover monitoring of social media over the past four years, and because of the use of more complex undercover operations that sometimes last for a number of years.