In 2013, the Kremlin resourced and launched a multiyear global operation to subvert democracy. The operation’s main weapon was intentionally harmful information—disinformation—spread through networks of paid trolls, bot networks, and users around the world. The information was aimed at sowing division within democracies and between democracies, particularly in NATO and the European Union. Some governments chose stronger responses than others. What explains the variation in government responses? I argue that each democracy’s combination of will and capability determined its response and that states with similar endowments of will and capability chose similar policies. I conduct an in depth cross-national of thirteen Western democracies supported by two case studies of specific states: Finland and the United States. My findings show that Kremlin disinformation has repeatedly adapted to changing contexts over the last century, is likely to continue adapting, and that Kremlin tactics having shown effectiveness, have spread to more state governments and even domestic actors. Future attacks will likely follow similar themes and patterns, so the lessons learned in this dissertation can help inform future responses.