When P.W. Singer set out to write a book about military use of social media in 2013, he couldn't have known exactly what kind of rabbit hole he was entering. The half-decade that followed would see social media power the rise of the Islamic State, elevate white nationalist movements and serve as a tool for a foreign actor seeking to undermine an American presidential election. In LikeWar: The Weaponization of Social Media, Singer and co-author Emerson Brooking fit phenomena like these into a broader narrative about the fast-evolving nexus of propaganda, digital marketing and psychological warfare. In their conception of weaponized social media, everyone from brand marketers and reality stars to terrorist recruiters and military personnel are now competing with one another in a viral attention battleground where troll armies, misinformation and bot networks are weapons of choice. Singer spoke with Adweek about how this social media atmosphere evolved, why brands need to pay attention to Russian bots and how artificial intelligence personas could be the future of online propaganda.