Fmr. top NSA lawyer on how to fight the national security threat of disinformation online

Glenn Gerstell, the National Security Agency's former general counsel joins Andrea Mitchell to talk about actions that need to be taken to stop the spread of misinformation online, including about vaccines. "For many, many years anti-vaccination websites have enjoyed a field day on Facebook for quite some time, fueling their falsehoods about the efficacy of vaccines," he says.