Book excerpt: Debates over the U.S. global defense posture are not new. As policymakers today evaluate the U.S. forward military presence, it is important that they understand how and why the U.S. global posture has changed in the past. Today's posture is under increasing pressure from a number of sources, including budgetary constraints, precision-guided weapons that reduce the survivability of forward bases, and host-nation opposition to a U.S. military presence. This monograph aims to describe the evolution of the U.S. global defense posture from 1783 to the present and to explain how the United States has grown from a relatively weak and insular regional power that was primarily concerned with territorial defense into the preeminent global power, with an expansive system of overseas bases and forward-deployed forces that enable it to conduct expeditionary operations around the globe. This historical overview has important implications for current policy and future efforts to develop an American military strategy, in particular the scope, size, and type of military presence overseas. As new and unpredictable threats emerge, alliance relationships are revised, and resources decline, past efforts at dealing with similar problems yield important lessons for future decisions. The author draws recommendations out of these lessons that touch on the importance of strategic planning; the need to think globally; the desirability of a lighter, more agile footprint overseas; and more.