The Trump administration is planning to transport a group of immigrants to Libya on a U.S. military plane, according to U.S. officials, another sharp escalation in a deportation program that has sparked widespread legal challenges and intense political debate.

The nationalities of the migrants were not immediately clear, but a flight to Libya carrying the deportees could leave as soon as Wednesday, according to the officials, who spoke on the condition of anonymity because they were not authorized to discuss the operation.

The decision to send deportees to Libya was striking. The country is racked with conflict, and human rights groups have called conditions in its network of migrant detention centers “horrific” and “deplorable.”

The Libya operation falls in line with the Trump administration’s effort to not only deter migrants from trying to enter the country illegally but also to send a strong message to those in the country illegally that they can be deported to countries where they could face brutal conditions. Reuters earlier reported the possibility of a U.S. deportation flight to Libya.

The planning for the flight to Libya has been tightly held, and could still be derailed by logistical, legal or diplomatic obstacles.

The White House declined to comment. The State Department and Defense Department did not immediately respond to requests for comment.