From 2011 through 2015, the DoD plans to spend over $336 billion to operate, maintain, modernize, and recapitalize its tactical air forces. Since DoD projects tactical aircraft inventory shortfalls over the next 15 years, it must effectively balance resources between an increasingly expensive Joint Strike Fighter program and the need to keep its legacy aircraft viable. This report assessed DoD's tactical aircraft requirements, the extent to which plans for upgrading and retiring legacy aircraft and acquiring new aircraft are likely to meet the requirements, and how changes in strategic plans and threat assessments have affected requirements. The report analyzed tactical aircraft requirement and inventory data, plans and threat assessments.