The author of this paper--an experienced and highly regarded terrorism specialist--provides a learned narrative about the scholarship and doctrine concerning terrorism and insurgency. The premise of the paper is that terrorism in the 21st century has become predominately international in nature, riding on the back of opportunities provided by new technologies in cyberspace, aerospace, and the Internet. In offering his thoughts about the well-chronicled flow of terrorism analysis, Dr. Sloan identifies how such recent trends should be affecting counterterrorism doctrine and policy. He suggests that traditional concepts for countering terrorism and insurgency are not effective in dealing with contemporary terrorism in its modern form as a non-territorially based insurgency. In the concluding parts of this monograph, Dr. Sloan addresses a number of additional views for improving upon the traditional approaches in order to deal with international and virtual threats, including a need to be keenly focused upon countermeasures for terrorist’s use of aerospace and cyberspace.