This chapter applies the conceptual framework of knowledge management (and vehicles familiar from that discipline) to analyze various aspects of knowledge as a resource for terrorist-organizations, and for confronting them, in the post-modern era. Terrorism is a societal phenomenon, closely integrated with changes in our knowledge society. Terrorist organizations became knowledge-centric, networked organizations, with a post-modern approach to organizational paradigms. Cyberspace is habitat for knowledge and information, and terrorists are knowledge workers proficient in it. Cyber terrorism is the convergence of cyberspace and terrorism, and is closely entwined with “nonvirtual” terrorist activities and global terrorism. IT allows terrorists similar societal power-shift – from large organizations to small groups and individuals. The chapter reviews the changing nature of terrorism towards postmodern terrorism and towards “learning terrorist organizations” implementing knowledge, cyber terrorism and cyber planning. Since it takes a network to beat a network, the chapter discusses knowledge and knowledge management (KM) in counterterrorism. Through ‘NetWar,’ conducted also in cyberspace (not necessarily aimed at the IT systems it uses as a platform—but rather at human lives), implementing familiar vehicles from the KM toolkit such as social network analysis (SNA), to KM in intelligence and KM in low intensity conflicts. Knowledge management proves salient both for terrorism and for countering it in a knowledge society.