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

The Trump administration violated a previous court order when it deported at least six migrants to South Sudan, a federal judge ruled Wednesday.

Immigration authorities refused to say what their final destinations would be, but said their home countries had refused to receive the migrants.

The Department of Homeland Security under President Donald Trump is preparing to deport a plane full of migrants from various countries to South Sudan — a nation teetering on the brink of civil war — defying a court order to do so,