The reality of voting security in America

On Thursday, President Trump gave a primetime address in which he sowed doubts about the integrity of U.S. election. He tried to convince Americans that the election system was vulnerable to fraud, but offered no new evidence that details any fraudulent votes. Instead, he declassified intelligence documents that he says will demonstrate "shocking vulnerabilities in our election infrastructure." What's in these documents - and what do they tell us about how elections are run in the US?