Answer by taking a quote from the following article:

Cass Robert Sunstein FBA (born September 21, 1954) is an American legal scholar, particularly in the fields of constitutional law, administrative law, environmental law, and law and behavioral economics, who was the Administrator of the White House Office of Information and Regulatory Affairs in the Obama administration from 2009 to 2012. For 27 years, Sunstein taught at the University of Chicago Law School. Sunstein is the Robert Walmsley University Professor at Harvard Law School. He is Honorary Doctor at Copenhagen Business School.

Sunstein co-authored a 2008 paper with Adrian Vermeule, titled "Conspiracy Theories," dealing with the risks and possible government responses to conspiracy theories resulting from "cascades" of faulty information within groups that may ultimately lead to violence. In this article they wrote, "The existence of both domestic and foreign conspiracy theories, we suggest, is no trivial matter, posing real risks to the government's antiterrorism policies, whatever the latter may be." They go on to propose that, "the best response consists in cognitive infiltration of extremist groups", where they suggest, among other tactics, "Government agents (and their allies) might enter chat rooms, online social networks, or even real-space groups and attempt to undermine percolating conspiracy theories by raising doubts about their factual premises, causal logic or implications for political action." They refer, several times, to groups that promote the view that the US Government was responsible or complicit in the September 11 attacks as "extremist groups."  The authors declare that there are five hypothetical responses a government can take toward conspiracy theories: "We can readily imagine a series of possible responses. (1) Government might ban conspiracy theorizing. (2) Government might impose some kind of tax, financial or otherwise, on those who disseminate such theories. (3) Government might itself engage in counterspeech, marshaling arguments to discredit conspiracy theories. (4) Government might formally hire credible private parties to engage in counterspeech. (5) Government might engage in informal communication with such parties, encouraging them to help." However, the authors advocate that each "instrument has a distinctive set of potential effects, or costs and benefits, and each will have a place under imaginable conditions. However, our main policy idea is that government should engage in cognitive infiltration of the groups that produce conspiracy theories, which involves a mix of (3), (4) and (5)."  Sunstein and Vermeule also analyze the practice of recruiting "nongovernmental officials"; they suggest that "government can supply these independent experts with information and perhaps prod them into action from behind the scenes," further warning that "too close a connection will be self-defeating if it is exposed." Sunstein and Vermeule argue that the practice of enlisting non-government officials, "might ensure that credible independent experts offer the rebuttal, rather than government officials themselves. There is a tradeoff between credibility and control, however. The price of credibility is that government cannot be seen to control the independent experts." This position has been criticized by some commentators who argue that it would violate prohibitions on government propaganda aimed at domestic citizens. Sunstein and Vermeule's proposed infiltrations have also been met by sharply critical scholarly critiques.

What is it about
Government agents (and their allies) might enter chat rooms, online social networks, or even real-space groups