Today, President-elect Donald Trump announced he was adding a third general to his cabinet: John Kelly, a retired Marine general, who Trump tapped to serve as Secretary of Homeland Security.

A four star general, Kelly led troops in combat in western Iraq. He also directed U.S. Southern Command, which coordinates military activities in South and Central America.

Juliette Kayyem, homeland security expert and host of "The SCIF" podcast, said Kelly's wide range of experiences would serve him well in the role of Homeland Security Secretary.

"Southern Command is essentially a diplomatic role, a pseudo-ambassadorial role," Kayyem explained. "It's about training Latin American and southern American countries. It's about trade and increasing trade. And, of course, it's about immigration."

Kelly is also the highest ranking general to have lost a child in the wars in Iraq and Afghanistan. His son, Robert, was killed by a concealed bomb in Afghanistan in 2010.

That experience has shaped Kelly's conception of warfare and the sacrifices it requires, says Kayyem.

"He has a deep sense—at least, when I've seen him and heard him speak and read the things he's written—a deep sense of the intimacy of what it means to be waging wars. It's the parents and the spouses and those who have lost people," she said.

To hear more from Juliette Kayyem, tune in to Boston Public Radio above.