Every day, millions of young people swap selfies on Snapchat, update their status on Facebook, and swipe right on love interests on Tinder. For millennials, social media is essential for a 21st Century social life — but for 62-year-old political scientist Eliot A. Cohen, it apparently means the end of the human civilization as we know it. For malevolent actors ranging from the government of Vladimir Putin to the recruiters of the Islamic State, social media is a weapon which can undermine American democracy and even topple entire governments.

In LikeWar: The Weaponization of Social Media, authors Peter W. Singer (Ghost Fleet) and Emerson T. Brooking (Interesting Times) examine this new 21st century way of war. It’s a battlefield whose soldiers are Russian trolls and whose generals include a World of Warcraft player who proved Russian forces downed a passenger jet over Ukraine. Most importantly, it’s a battlefield in which every American is a potential target.

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Prior to her online spat with Kim Kardashian, pop princess Taylor Swift was a social media powerhouse. The ten-time Grammy Award singer spent hours each day interacting with her fans on Tumblr and Instagram, often leaving comments on her fans’ posts and paying homage to Internet memes. Her relationship with fans was effective because it felt authentic. Swift called the practice #Taylurking; PR professionals call it brand engagement. It’s a technique that celebrities, politicians, and even senior military leaders use to connect with fans, voters, and soldiers.

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What does Taylor Swift have to do with 21st-century war? LikeWar details how ISIS fighters deliberately adopted Swift’s sense of authenticity to attract recruits. Western fighters who flocked to Syria didn’t just post pictures of battlefield exploits: Many normalized life in the ISIS by sharing pictures of themselves playing with cats or mourning the death of actor Robin Williams. Much like Taylor Swift did with her fans, ISIS fighters used this sense of authenticity to reach out to disaffected youths in the West, promising lonely recruits a sense of camaraderie and adventure in the so-called caliphate.

Counter-terrorism experts desperately tried to blunt ISIS’s social media onslaught. But while the U.S. government poured millions into counter-messaging programs on social media, including the State Department’s “Think Again, Turn Away”, many of these programs were generally ineffective. Instead, LikeWar argues that the best antidote to ISIS’ messaging is peer-to-peer engagement – same kind pioneered by both Taylor Swift and ISIS fighters.

Consider Farah Pandith, a Kashmiri woman who served as America’s first-ever representative to Muslim communities. Pandith assembled a team of online teenage volunteers throughout the world often dubbed “Dumbledore’s Army” after the Hogwarts students who fight evil in the Harry Potter novels. According to Pandith, fellow teenagers are best equipped to reach out those most susceptible to ISIS messaging and dissuade them from joining or interacting with ISIS fighters. In the 21st Century LikeWar, some of the best weapons don’t pew-pew.

Fake news, real consequences

Beyond the contours of modern digital propaganda, LikeWar also delves into the wild and weird world of “fake news.” Of course, fake news long predated the Internet: In the early 18th century, the New-England Courant published a series of letters purportedly written by an elderly lady named “Mrs. Silence Dogood” that were actually authored by a 16-year old Benjamin Franklin. Throughout the years, people have eagerly gobbled up all sorts of zany conspiracy theories; one of the longest-running and most successful shows on the History Channel is Ancient Aliens, now in its thirteenth season with an increasingly tenuous grasp on “history.”

However, fake news can have real-world consequences, perhaps even fatal. In December 2016, a man armed with a semi-automatic rifle burst into Comet Ping Pong Pizza in Washington, DC demanding answers about a ridiculous conspiracy theory which claimed the restaurant held dozens of child sex slaves in the basement. (Spoiler: there was no basement, let alone child sex slaves)

Related: An Alarming Guide To The National Security Dangers Of Social Media »

#Pizzagate wasn’t the first time online misinformation caused a real-life confrontation. In May 2016, protestors gathered outside an Islamic center in Houston to denounce the “Islamization of Texas” while counter-protestors rallied to “Save Islamic Knowledge”. The group’s organizers weren’t from the Lone Star State, however – they were from a grey building in St. Petersburg, Russia, belonging to the “Internet Research Agency”, where paid trolls have pumped out fake news since at least 2014. Russian trolls even managed to coax an unwitting American to stand in front of the White House with a sign reading “Happy 55th Birthday, Dear Boss.”

Unbeknownst to the hapless American, “Dear Boss” was really Yevgeniy Preigozhin, a former chef for Vladimir Putin who headed the IRA and is a leading figure within a Russian Private Military Corporation which was recently involved in a massive firefight with U.S. troops in Syria. Making matters worse is that other nations have adopted Russia’s online tactics, with Facebook recently deleting hundreds of phony accounts linked to the Iranian government and aimed at spreading propaganda throughout the Middle East and the West.

But as the authors are keen to note, a barrage of online ads won’t affect human behavior on their own. Russia’s online armies didn’t hack our computers so much as they also hacked our brains. Fear and anger – not happiness – makes content go viral, and Russian trolls worked diligently to stoke it. Virtual trolling has even spilled over into the real world, spurring violence in Western nations.

Silicon Valley strikes back

LikeWar ends with a plea for tech giants to police their platforms for misinformation, propaganda, and hate speech. As this book is going to press, Silicon Valley is doing just that, often at great cost to their stockholders. Twitter lost 21 percent of its value after reportedly deleting over one million fake accounts each day, contributing to a net loss in the number of users. Facebook, likewise, just suffered the largest stock market tumble in history, losing $150 billion in just two hours.

Though the relationship between Silicon Valley and Washington has been strained in the wake of the Snowden leaks as well as the intelligence community’s “stockpiling” of cyber vulnerabilities, tech companies are stepping up to battle online misinformation. This past week, Facebook and Alphabet (the parent company for Google) deleted hundreds of fake accounts linked to both the Russian government as well as Iran’s state media organization. Microsoft, for its part, recently exposed a plot by Russia’s “Fancy Bear” hackers – the same ones recently indicted for their role in the 2016 election – to hack Republican party officials who supported sanctions against Russia.

Swipe right

Make no mistake: the world is at war on the Internet. Although pundits (including co-author Peter Singer) have written extensively about cybersecurity, few grasp the real threat Americans face on their favorite social networks in the course of their daily experiences. Through amusing vignettes and plenty of pop-culture references, the authors take us on a wild ride featuring everything from reality TV stars to Russian missiles.

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