WASHINGTON — The first U.S. military flight to deport migrants from the United States to Guantanamo Bay was set to depart Tuesday, a U.S. official said. It is the first step in what is expected to be a surge in the number of migrants held at the Navy base in Cuba, which for decades was primarily used to detain foreigners associated with the Sept. 11, 2001, attacks.

President Donald Trump has eyed the facility as a holding center and said it has the capacity to hold as many as 30,000.

Defense Secretary Pete Hegseth, who was assigned to Guantanamo Bay when he was on active duty, has called it a “perfect place” to house migrants. Additional U.S. troops have arrived at the facility in the past few days to help prepare it.

In addition, the U.S. flew Indian migrants back to India on Monday, and that flight was still in progress as of midday Tuesday, the U.S. official said. The official spoke on the condition of anonymity to provide details not yet made public.

There had previously been seven deportation flights, to Ecuador, Guam, Honduras and Peru. In addition, Colombian officials flew to the U.S. and took two flights of migrants back to their country.

There are approximately 300 service members supporting the holding operations at Guantanamo Bay, and the numbers will fluctuate based on the requirements of the Department of Homeland Security, which is the lead federal agency.

CNN was first to report on the flights.