President Trump’s Pentagon has just ordered the military to prepare large aircraft such as C-130s and C-17s to be used in the mass deportations, specifically for repatriation flights:

 
CNN mentions it in their article announcing over 2,000 active duty forces being sent to the southern border:

There are already roughly 2,200 active duty forces at the border as part of Joint Task Force-North, US Northern Command’s border mission based out of El Paso, Texas. They help support US Customs and Border Protection’s work there, performing mostly logistical and bureaucratic tasks like data entry, detection and monitoring, and vehicle maintenance.

It is not yet clear which specific units are being ordered to the border, but an initial wave will include around 1,500 troops.

Acting Secretary of Defense Robert Salesses said he directed the Defense Department to “begin augmenting its forces at the southwest border” with 1,500 ground personnel “as well as helicopters with associated crews, and intelligence analysts to support increased detection and monitoring efforts.”

“[T]he Department will provide military airlift to support DHS deportation flights of more than five thousand illegal aliens from the San Diego, California, and El Paso, Texas, sectors detained by Customs and Border Protection,” Salesses said in a statement. “DHS will provide inflight law enforcement, and the State Department will obtain the requisite diplomatic clearances and provide host-nation notification.”

“This is just the beginning,” Salesses added. Two sources previously told CNN that US Transportation Command had been instructed to prepare to use US military assets, including military aircraft, for migrant repatriation flights.

The number of Marines deployed as part of the border mission could ultimately climb to 2,500, the official said.

There is also a National Guard contingent at the border called Operation Lonestar, headed by the Texas National Guard. There are roughly 4,500 National Guardsmen currently assigned to the mission, according to the Texas Military Department.

The additional active duty troops being sent to the border this week will be doing much of the same, the officials said, and are expected to feed into and augment Joint Task Force-North.

They will be helping to maintain operational readiness for Border Patrol, assisting in command-and-control centers, and providing more intelligence specialists to assess threats and migrant flows, according to sources familiar with the planning.