Recent work has begun exploring the effects of foreign military deployments on hoststate foreign policies. However, research mostly focuses on dyadic relationships between major powers and host-states, ignoring the broader regional security environment of host-states. We develop a theory of spatial hierarchies to understand how security relationships throughout the region surrounding the host-state affect hoststate foreign policy. Using data on US military deployments from 1950-2005, we show that regional security considerations condition how host-states respond to the deployment of military forces to their territory. Consequently, regional analyses are fundamental in understanding monadic and dyadic decisions about security, alliance behavior, and conflict.Major powers have a history of deploying their military forces to project power. In spite of their importance, international relations research contains little work on the consequences of such deployments. However, scholars have begun examining a range of issues associated with US military deployments, including economic growth, trade, investment, security policy, conflict behavior, and crime (Martinez Machain and Morgan 2013). While this research area has grown, the role that such deployments play in the regional security environment remains under-explored. Accordingly, interpretations of causality in existing studies is incomplete as the regional context exerts a conditioning effect upon the relationships of interest. Fundamentally, regional security contexts should affect how states respond to the presence of foreign military forces.Herein we examine how US military deployments affect foreign policy decisions. We build upon previous studies by incorporating regional security factors into our theoretical argument and analysis. Using data on US military deployments since 1950, we analyze how US military deployments to a host-state, as well as deployments to third-party states in the region, affect these states' defense spending decisions. Studies typically focus on the host-state's response to US troop deployments in a dyadic fashion, evaluating how US deployments affect the host-state's military spending or conflict propensity (e.g. Allen, Flynn and VanDusky-Allen 2014; Lake 2009a; Martinez Machain and Morgan 2013). This approach assumes that the effects of US military deployments on a particular state are independent of military deployments in neighboring states and the regional security environment. * The authors would like to thank David Lake, Pat Shea, Carla Martinez Machain, Chad Clay, the editorial team at International Interactions, and two anonymous reviewers for their comments and suggestions. Replication files can be found at the International Interactions Dataverse page: http://dvn.iq.harvard.edu/dvn/dv/internationalinteractions. Questions regarding replication materials can be directed to meflynn@ksu.edu.
2This variable is the sum of the CINC scores for pairs of states with an S score that is less than the global median S score, calculated for al...