Twitter trolls run by the Kremlin's Internet Research Agency. Denial of service attacks and ransomware deployed across Ukraine. Spies hidden in the heart of Wall Street. And a century-old fabricated staple of anti-Semitic hate literature. At first glance these disparate phenomena might seem only vaguely connected. Sure, they can all be traced back to Russia. But is there any method to their badness? The definitive answer, according to Russia experts inside and outside the US government, is most certainly yes. In fact, they are part of an increasingly digital intelligence playbook known as "active measures," a wide-ranging set of techniques and strategies that Russian military and intelligence services deploy to influence the affairs of nations across the globe. As the investigation into Russia's influence on the 2016 election--and the Trump campaign's potential participation in that effort--has intensified this summer, the Putin regime's systematic effort to undermine and destabilize democracies has become the subject of urgent focus in the West. According to interviews with more than a dozen US and European intelligence officials and diplomats, Russian active measures represent perhaps the biggest challenge to the Western order since the fall of the Berlin Wall. The consensus: Vladimir Putin, playing a poor hand economically and demographically at home, is seeking to destabilize the multilateral institutions, partnerships, and Western democracies that have kept the peace during the past seven decades.