Guantánamo Bay, Cuba - US Immigration and Customs Enforcement has started sending detained migrants to the Guantánamo Bay detention camp, the Department Defense announced Tuesday.

ICE has deported approximately 20 migrants to Guantánamo Bay in Cuba on Tuesday, the DOD announced, but no information is yet available on the nationalities or identities of those imprisoned there, the New York Times reported.

Rumors started swirling when flight trackers followed a plane that left a Department of Homeland Security-run airport on Monday.

Guantánamo Bay has reportedly not held any migrant detainees since October 1. The admission of at least 20 new people to the facility brings the total number of migrants imprisoned there to approximately 710 since the Trump administration launched its mass deportation campaign.

A spokesperson for DHS refused to respond to requests for comment from the NYT, neither confirming why the detention camp was first cleared of migrants nor why it is being repopulated.

Guantánamo Bay is a notorious facility that was first established by former President George W. Bush in 2002 to hold terrorism suspects and prisoners of war. It has become famous for housing people – most of whom were not even charged with crimes – in brutal, inhumane, and unsanitary conditions.

The US has subjected many people detained there to abuse and torture under the guise of so-called "enhanced interrogation."

Civil liberties lawyers are suing to have Trump banned from using Guantánamo Bay as a migrant detention facility because it was never intended to be used "for the purpose of civil immigration detention," NYT reported.

"Nor is there any legitimate reason to do so," the legal filing argues. "The government has ample detention capacity inside the United States."