On his first day in office, Trump took steps to designate the Tren de Aragua gang a “foreign terrorist organization” alongside several Mexican drug cartels.

The Trump administration has sparked controversy with its move Sunday to deport 261 people, some of whom it alleges are members of the Venezuelan gang Tren de Aragua, to an infamous maximum-security prison in El Salvador.

The Trump administration has invoked a 227-year-old law, the Alien Enemies Act, to target Tren de Aragua, a gang with its roots in the prisons of Venezuela. Who are they and how wide is their reach?