Not all know it, but we are witnessing a revolution in military technology. Increasingly, unmanned systems are taking on the ‘dull, dirty and dangerous’ roles in the military. We already have unmanned systems that crawl, swim and fly, performing mine disposal, surveillance and more direct combat roles, to name only a few. These systems have found their way into the military force structure quite rapidly, giving rise to a debate concerning the ethics of their use. Some are opposed to their use, raising a number of ethical, legal and operational issues, while others are keen to take advantage of the benefits they offer. This book examines the case for the use of unmanned systems through the lens of just war theory, exploring the various problems associated with their employment.