This is an episode from our archives. Since we published this episode, the Wall Street Journal released a report that the Pentagon purposely spread disinformation about UFOs, at times to protect secret military operations.

Have we been visited by extraterrestrial life? And how much does the government really know when it comes to UFOs? Garrett Graff’s latest book, UFO: The Inside Story of the US Government’s Search for Alien Life Here — and Out There, investigates these questions and more. The national-security reporter recently sat down with Apple News In Conversation host Shumita Basu to share his findings.