Elite tracking squads called mobile surveillance teams are assigned to the suspects 24/7 within the United States, according to Fox.
“There is a very significant number of people that are on suspicious watch lists, under surveillance,” Republican Indiana Sen. Dan Coats, a member of the Select Committee on Intelligence, told Fox. “The FBI, together with law enforcement agencies across the country, are engaged in this.
Enormous amounts of manpower and money are required for the round-the-clock operations, Coats said. At least a dozen agents are assigned to each suspect.
The recent Paris attacks taught law enforcement that radicalization can happen quickly. Hasna Ait Boulahcen, the female suspect killed in a shootout in Saint Denis had been involved in partying just a month before the Paris attacks, her friends said.