If President-Elect Donald Trump indeed builds a wall — or a fence in some parts — across the U.S.-Mexican border, his prospective pick to run the Department of Homeland Security would be heavily involved.

Trump has tapped retired Marine Gen. John Kelly as DHS secretary, according to published reports. A four-star general, like prospective Defense secretary James Mattis, Kelly’s most recent assignment, which ended in February, was heading the U.S. Southern Command, which oversees the U.S. detention center at Guantanamo Bay, Cuba.

As head of the DHS, the U.S. federal government’s third largest department, Kelly would call the shots around border protection and immigration, airport security, and the Coast Guard, among other duties.

There isn’t much insight yet as to which directions Kelly would tilt the Transportation Security Administration, which is responsible for airport security. The TSA faces abundant challenges such as an expected influx of travelers in coming years, overloaded security lanes, the need to further automate them, staff and resource shortages, and the requirement to get better at threat detection.

It wouldn’t be a stretch under a Trump administration to see further calls to privatize airport security. There is already a movement afoot to accelerate the proliferation of TSA Precheck through partnerships with third-party vendors.

Kelly, whose Marine son died in Afghanistan in 2010, is likely to spearhead a drive under the Trump Administration to focus on immigration, illegal and otherwise. During Kelly’s three-year stint heading the U.S. Southern Command, it worked to disrupt efforts to smuggle immigrants into the country in south Florida and cooperated with U.S. Customs and Border Protection to rescue kids who arrived solo at U.S. crossing points, according to the Associated Press.

Kelly, 66, serviced in the U.S. Marine Marine Corps from 1970 to 2016. When he retired from the Marines and his post heading the U.S. Southern Command in February, he commented on the Marines’ initial opposition to allowing women to be combat soldiers. Kelly said he feared that allowing women into these roles would lead to a reduction in standards.

Unlike Mattis, who would be nominated to be Defense Secretary, Kelly would not need a waiver, as a former and recently retired Marine, to lead DHS.

Kelly’s appointment would be subject to Senate confirmation hearings.

Photo Credit: President-Elect Trump will reportedly nominate retired Major Gen. John Kelly to lead the Department of Homeland Security. U.S. Department of Defense