Turkey's president has announced the start of an invasion as Kurdish forces move to defend the Turkish-Syrian border. The Kurds have been essential allies in the U.S. fight against ISIS, but President Trump announced he'd be abandoning them, breaking an American promise and pulling out of the region to allow Turkey to attack. CBS News correspondent Natalie Brand reports on the latest, and CBS News national security correspondent David Martin joined CBSN to discuss the military offensive.
