A group of lawmakers is calling on Secretary of State Antony Blinken to do more to address an increasing number of Havana Syndrome cases among U.S. officials. In a letter obtained by CBS News, they call the situation a "significant, unmitigated threat to our national security." Suspected cases of Havana Syndrome have been reported in several countries in recent weeks. Intelligence and national security reporter Olivia Gazis joined CBSN's Lana Zak to discuss.
