It would be nice to be able to predict the future, although the success of Cassandra’s curse may be a warning that accurate prediction alone is never enough. At this point in time, however, the situation is so volatile and unpredictable that it is not possible to predict a future in which the threat of covert attacks by state actors, their proxies, or independent extremists and terrorists requires a major homeland defense effort. The United States and its citizens are almost certain to come under attack in some form, but it is not yet clear that such attacks will involve methods of attack that produce mass casualties or mass destruction. A trend analysis and an assessment of current threats indicate that such a future is possible, but it does not firmly indicate that it is probable.
At the same time, the analysis of possible methods of attack and the evolving technologies involved indicate that the United States cannot prudently ignore the risk that CBRN weapons will be used against the U.S. homeland in the future and that there are no technical barriers to such use in the near term. Leaving a power vacuum in terms of credible deterrence and retaliation, active detection and defense within U.S. territory, and effective response measures will create an open invitation to strike at the U.S. homeland in an era where asymmetric warfare is the only counter that most of America’s enemies have to its conventional military power. It also risks making the U.S. homeland a hostage to the threat of such attacks when enemies attack U.S. friends and allies.