U.S. Army Colonel Lonnie Carlson (Ph.D.) and Dr. Margaret Kosal argue that WMD expertise must be built within the SOF enterprise and that SOF must collaborate with government organizations (both U.S. and partner nation) to conduct WMD counterproliferation-related building partnership capacity (BPC) and operational preparation of the environment (OPE) activities. The authors look at SOF attributes and assert that it is within the irregular warfare domain that SOF have the greatest opportunity to improve WMD counterproliferation effectiveness. The authors present a brief explanation of WMD classifications, present an inventory of countries who possess weapons-grade nuclear material, and graphically present the potential cost versus probability of use for WMD types. Colonel Carlson and Dr. Kosal conclude that the U.S. Government and Department of Defense must build and leverage the global SOF network through CWMD OPE and BPC activities. Those activities can lead to the early warning needed to mitigate fleeting opportunities to eliminate catastrophic WMD risks.