In a Sept. 15 department-wide memo, Austin asked personnel to quickly report potential cases of "Anomalous Health Incidents." In recent years, Pentagon personnel working primarily overseas have reported "sudden and troubling" sensory events that include sounds, pressure or heat. U.S. diplomatic and military personnel have reported cases of what's been called "Havana Syndrome." More recently, U.S. Vice President Kamala Harris delayed a diplomatic trip to Vietnam in August because of threats resembling Havana Syndrome. Eavesdropping technology from Russia's military intelligence agency was used in some cases.