DHS cybersecurity head: 'No doubt' Russians penetrated voter registration systems

In an exclusive interview with NBC News' Cynthia McFadden, Jeanette Manfra, the head of cybersecurity at the Department of Homeland Security, says that 21 states were targeted during the 2016 election. See more Wednesday on NBC Nightly News With Lester Holt. CORRECTION: This Nightly News segment has been updated to correct a map of 21 states that officials say were targeted by Russian hackers. Our original report incorrectly showed Georgia and omitted Alaska. Georgia is not one of the 21 targeted states; Alaska is.