White House Press Secretary Karoline Leavitt said Tuesday the first flights of undocumented immigrants from the U.S. to Guantánamo Bay in Cuba were underway—following an escalation of arrests across the country as part of what President Donald Trump has promised would be the “largest deportation operation” in U.S. history.

The Trump administration has carried out 10 deportations on military planes. The flights cost more and move fewer, an El Paso Times analysis found.

Military planes are being used for deportations to expedite the process quickly and efficiently, with little concern for costs, as part of Donald Trump's national emergency on illegal immigration.