The United States Air Force is said to be evolving into an air and space force on its way to becoming a space and air force. An integral part of this transition involves the possibility of deploying weapons in space. While there is a growing literature about the need for weapons in space or, conversely the need to ensure that space remains a weapons-free sanctuary, little has been written about what space-based weapons can and cannot bring to the battlefield. A decision to put weapons in space-or to refrain from doing so-should be based on a firm understanding about what such weapons can be expected to achieve. More specifically since numerous orbital weapons concepts have been advocated as natural evolutions of surface and airborne weapons, it would appear useful to compare those proposed space-based systems with their terrestrial counterparts. Does the United States Need Space-Based Weapons? by Maj. William L. Spacy II evaluates the theoretical capabilities of orbital weapons and compares them to weapons already in existence and to emerging concepts proposed for development. His primary objective is to suggest where future investments should be made if the United States is to protect its increasingly important space-based assets and retain its position as a global leader able to project military power wherever necessary.