It’s been a little over a week since the U.S. military shot down a Chinese surveillance balloon over the coast of South Carolina. Since then, the United States has downed at least an additional three unidentified crafts in North American airspace. The balloon saga has put a spotlight on foreign espionage operations, but Javed Ali said the practice is nothing new. Ali is a former senior national security and intelligence official, as well as an associate professor of practice at the University of Michigan. He spoked to Marketplace’s Kimberly Adams about what we can glean from this string of incidents about the technology and practices used in modern international espionage.