Contrary to ill-founded expectations, the end of Cold War did not eliminate the threat of weapons of mass destruction (WMD). Although we have likely escaped the danger of a nuclear Armageddon, the presence and proliferation of WMD continue to pose a serious threat to today's global security. Today, WMD and their delivery vehicles are still perceived by many countries as necessary or highly desirable weapons for a variety of reasons, including as a deterrent against security threats, as a force equalizer to compensate conventional military capabilities, as prestige and status enhancers, and for bolstering regime security. The aim of this volume is to analyze some of the key issues which concern the presence and proliferation of WMD in the post-Cold War international system, and thereby advance understanding on such a critical and, unfortunately, still very topical problem.