A federal judge ruled late Tuesday that U.S. officials must retain custody and control of migrants apparently removed to South Sudan in case he orders their removals were unlawful.

A federal judge in Boston has told the Trump administration it must to maintain custody of migrants whom the US government has allegedly flown to South Sudan or other countries in recent days amid heightened concerns over the administration’s aggressive approach to deportations.

The deportees are stuck in Djibouti amid a legal fight over their expulsions. A lawyer for some of the men said she was concerned for their health and welfare.