The main risk is spread of false news and, possibly, some sort of panic through social media. mainstream media tends to pick those news up and spread it further. For those who live in the West, the risk have become lesser than decade ago, because more people are starting to take everything with a grain of salt. Another consequence is that people trust media even less than before, which is causing problems for media companies. At some point those large troll farms will become too expensive to maintain and no longer effective - it is a "cry wolf" effect. Those who live in closed societies are probably more vulnerable to psychological warfare, because they know that government is keeping things from them, and when some information breaks out, more people are willing to believe it. Closing the information space itself does not help if foreign agent is located inside the country. They still have to deal with internal censorship, but there are ways around it Once the information is out, it spreads like a wildfire, because people are eager for anything that has not been filtered by the government.