From the Foreword by General H.R. McMaster: Strategies that weaken illicit power structures and strengthen legitimate state authority are vital to national and international security. As Dr. Henry Kissinger observed, we may be “facing a period in which forces beyond the restraints of any order determine the future.” Because threats to security emanate from disorder in areas where governance and rule of law are weak, defeating terrorist, insurgent, and criminal organizations requires integrated efforts not only to attack enemy organizations, but also to strengthen institutions essential to sustainable security. Successful outcomes in armed conﬂict require confronting illicit networks. A failure to do so effectively frustrated efforts to consolidate gains in Afghanistan and Iraq, and after more than a decade of war and development, the international community and the governments of those countries, continue to contend with the violence and instability that are the result. In Afghanistan, corruption and organized crime networks perpetuate state weakness and undermine the state’s ability to cope with the regenerative capacity of the Taliban. The failure to counter militias and Iranian proxies that inﬁltrated the government and security forces in Iraq led to a return of large scale communal violence and set conditions (along with the Syrian Civil War) for the rise of a terrorist proto-state and a humanitarian catastrophe that has adversely impacted the entire Middle East. These and other cases illustrate how governments and international actors struggle to establish security and rule of law, and reveal incomplete plans and fragmented efforts that fail to address the causes of violence and state weakness. While challenging, success in confronting illicit power structures is not impossible. While still works in progress, successful efforts, such as those in Colombia and Sierra Leone, are the result of integrated diplomatic, military, economic, development, informational, intelligence, and law enforcement efforts directed toward well-deﬁned political outcomes. The case studies and analyses in this volume make clear that understanding the dynamics associated with illicit power and state weakness is essential to preventing or resolving armed conﬂict. These case studies also point out that confronting illicit power requires coping with political and human dynamics in complex, uncertain environments. People ﬁght today for the same fundamental reasons the Greek historian Thucydides identiﬁed nearly 2,500 years ago: fear, honor and interests. They further remind us that that illicit power structures often depend on the perpetuation of violence and the conﬂict economy. Crafting effective strategies to address the challenge of weak states must begin with an understanding of the factors that drive violence, weaken state authority, and strengthen illicit actors and power structures. Terrorist, insurgent, and criminal networks exploit fear and anger over injustice, portraying themselves as patrons or protectors of a community in competition with others for power, resources, or survival. Thus military and law enforcement capabilities provide only one component of what must be comprehensive, civilian and military approach to confronting illicit power.