Using an original data set of 145 ground, air, and naval interventions from 1898 through 2016, this report identifies those factors that have made U.S. military interventions more or less successful at achieving their political objectives. While these objectives were often successfully achieved, about 63 percent of the time overall, levels of success have been declining over time as the United States has pursued increasingly ambitious objectives. The research combines statistical analysis and detailed case studies of three types of interventions -- combat, stability operations, and deterrence. The research highlights that the factors that promote the successful achievement of political objectives vary by the nature of the objective and the intervention. For example, sending additional ground forces may help to defeat adversaries in combat missions but may have a more contingent effect on success in institution-building in stability operations, where nonmilitary resources and pre-intervention planning may be especially vital. The report offers five main policy recommendations. First, planners should carefully match political objectives to strategy because factors that promote success vary substantially by objective type. Second, sending more forces does not always promote success, but for certain types of objectives and interventions, greater capabilities may be essential. Third, policymakers should have realistic expectations regarding the possibility of achieving highly ambitious objectives. Fourth, pre-intervention planning is crucial. Finally, policymakers should carefully evaluate the role that might be played by third parties, which is often under appreciated.

One of the most contentious issues in contemporary foreign policy—especially in the United States—is the use of military force to intervene in the domestic affairs of other states. Some military interventions explicitly try to transform the domestic institutions of the states they target; others do not, instead attempting only to reverse foreign policies or resolve disputes without trying to reshape the internal landscape of the target state. In Leaders at War, Elizabeth N. Saunders provides a framework for understanding when and why great powers seek to transform foreign institutions and societies through military interventions. She highlights a crucial but often-overlooked factor in international relations: the role of individual leaders. Saunders argues that leaders' threat perceptions—specifically, whether they believe that threats ultimately originate from the internal characteristics of other states—influence both the decision to intervene and the choice of intervention strategy. These perceptions affect the degree to which leaders use intervention to remake the domestic institutions of target states. Using archival and historical sources, Saunders concentrates on U.S. military interventions during the Cold War, focusing on the presidencies of Eisenhower, Kennedy, and Johnson. After demonstrating the importance of leaders in this period, she also explores the theory's applicability to other historical and contemporary settings including the post–Cold War period and the war in Iraq.

"In recent years, the frequency of U.S. military interventions in overseas areas, including not only those involving conventional war but also peacekeeping and humanitarian relief operations, has risen. These interventions have involved thousands of troops, cost billions of dollars, and placed significant demands on Army leadership, planning, and resources. The Army would benefit from an enhanced ability to anticipate the types and conditions of overseas military interventions it is most likely to be called upon to undertake in the future. This report constructs three different sets of models using historical data (one for each of three intervention types: interventions into armed conflict, stability operations in conflict and postconflict environments, and deterrent interventions). It examines the key factors influencing the incidence of military interventions and intervention size. Finally, the analysis provides the Army with signposts and metrics that can be used to identify countries, conflicts, and crises that are at highest risk for a U.S. intervention. Key signposts include the relationship between the target of the intervention and the United States, past U.S. military involvement in that country, and the severity of the crisis or threat to which the United States is responding. These signposts would allow the Army to better anticipate and plan for future interventions and could improve both near- and medium-term force-planning decisions"--Publisher's description.

During the post--World War II era, American foreign policy prominently featured direct U.S. military intervention in the Third World. Yet the cold war placed restraints on where and how Washington could intervene until the collapse of the former Soviet Union removed many of the barriers to -- and ideological justifications for -- American intervention. Since the end of the cold war, the United States has completed several military interventions that may be guided by motives very different from those invoked before the collapse of the Berlin Wall. Likewise, such operations, now free from the threat of counterintervention by any other superpower, seem governed by a new set of rules. In this readily accessible study, political scientist Glenn J. Antizzo identifies fifteen factors critical to the success of contemporary U.S. military intervention and evaluates the likely efficacy of direct U.S. military involvement today -- when it will work, when it will not, and how to undertake such action in a manner that will bring rapid victory at an acceptable political cost. He lays out the preconditions that portend success, among them a clear and attainable goal; a mission that is neither for "peacekeeping" nor for "humanitarian aid within a war zone"; a strong probability the American public will support or at least be indifferent to the effort; a willingness to utilize ground forces if necessary; an operation limited in geographic scope; and a theater commander permitted discretion in the course of the operation. Antizzo then tests his abstract criteria by using real-world case studies of the most recent fully completed U.S. military interventions -- in Panama in 1989, Iraq in 1991, Somalia in 1992--94, and Kosovo in 1999 -- with Panama, Iraq, and Kosovo representing generally successful interventions and Somalia an unsuccessful one. Finally, he considers how the development of a "Somalia Syndrome" affected U.S. foreign policy and how the politics and practice of military intervention have continued to evolve since the terrorist attacks of September 11, 2001, giving specific attention to the current war in Afghanistan and the larger War on Terror. U.S. Military Intervention in the Post--Cold War Era exemplifies political science at its best: the positing of a hypothetical model followed by a close examination of relevant cases in an effort to provide meaningful insights for future American international policy.

Publisher Fact Sheet Draws upon case studies - including Iraq, Bosnia, Haiti, Somalia, & Lebanon - & suggests political & military guidelines for potential U.S. military interventions ranging from peacekeeping & humanitarian operations to preventative strikes & all-out warfare.

US Intervention Policy and Army Innovation examines how the US Army rebuilt itself after the Vietnam War and how this has affected US intervention policy, from the victory of the Gulf War to the failure of Somalia, the Bosnian and Kosovo interventions and the use of force post 9/11. Richard Lock-Pullan analyzes the changes in US military intervention strategy by examining two separate issues: the nature of the US Army as it rebuilt itself after the Vietnam War, and the attempts by the US to establish criteria for future military interventions. He first argues that US strategy traditionally relied upon national mobilization to co-ordinate political aims and military means; he subsequently analyzes how this changed to a formula of establishing militarily achievable political objectives prior to the use of force. Drawing on a vast body of material and on strategic culture and military innovation literature, Lock-Pullan demonstrates that the strategic lessons were a product of the rebuilding of the Army's identity as it became a professional all-volunteer force and that the Army's new doctrine developed a new 'way of war' for the nation, embodied in the AirLand Battle doctrine, which changed the approach to strategy. This book finally gives a practical analysis of how the interventions in Panama and the Gulf War vindicated this approach and brought a revived confidence in the use of force while more recent campaigns in Somalia, Kosovo and Bosnia exposed its weaknesses and the limiting nature of the Army's thinking. The legacy of the Army's innovation is examined in the new strategic environment post 9/11 with the operations in Afghanistan and Iraq.

Quigley analyzes each instance of military intervention abroad by the United States since World War II, from the perspective of what the government told the public--or did not tell the public.