The Berlin Wall of the Internet

President Donald Trump with China's President Xi Jinping during their bilateral meeting at the G20 Summit, Saturday, Dec. 1, 2018 in Buenos Aires, Argentina.

David Sanger, national security correspondent for The New York Times and the author of, now out in paperback, The Perfect Weapon: War, Sabotage, and Fear in the Cyber Age (Crown, 2018), talks about America's vulnerability to cyber attacks by global adversaries, including how the rise of China's Huawei could create two different — and opposing — cyber networks.