President Donald Trump last week invoked a centuries-old law to swiftly detain and deport Venezuelan migrants suspected of belonging to the Tren de Aragua gang.

By activating the 1798 Alien Enemies Act, he effectively classifies these suspected gang members as wartime adversaries of the U.S. government, granting his administration the power to arrest, detain, and deport them without due process.

The order specifies that any Venezuelan citizen aged 14 or older who is a gang member, residing in the U.S. without naturalization or lawful permanent resident status, is “liable to be apprehended, restrained, secured, and removed as Alien Enemies.”

On Saturday, Trump triggered a seldom-used law for the first time since World War II—a law that has been enacted only four times since its creation.

The president had already laid the groundwork earlier this year by signing an executive order in January that designated Tren de Aragua, a Venezuelan prison gang, as a foreign terrorist organization.