The U.S. has been testing a device that may be connected to Havana Syndrome, an illness that has caused symptoms like memory los...

The U.S. has been testing a device that may be connected to Havana Syndrome, an illness that has caused symptoms like memory loss and even brain injury in more than 1,000 people, but has remained a mystery for nearly a decade. Newsweek’s senior defense reporter Ellie Cook has the latest.