The Trump administration has abruptly cleared out a second group of migrants it brought to the American military base at Guantánamo Bay, Cuba, returning to the United States 40 men it had flown there in the past few weeks, according to officials familiar with the matter.

The government has not announced that it relocated the men to one or more Immigration and Customs Enforcement facilities in Louisiana, nor was the reason for the move clear. But the officials familiar with the matter, speaking on the condition of anonymity to discuss a sensitive issue, said it happened on Tuesday.

The move comes days before a Federal District Court judge in Washington is set to hear a major challenge to aspects of the policy.

It is the second time the administration has brought people to Guantánamo Bay only to remove them after a few weeks, a costly and time-consuming exercise.

In late February, the administration abruptly emptied two detention sites the government had used to hold 177 Venezuelans flown in from the United States, including a military prison building formerly used to hold terrorism detainees.

But in moving those detainees on Feb. 20, the administration repatriated the migrants to the custody of their home government. This time, the officials said, the men were taken to an international airport in Alexandria, La.