Facilities belonging to any of our military branches world-wide, offer our enemies significant targets for both real and political victories. Inflicting even the smallest amount of damage on the organized military forces of the United States is viewed as a victory in certain parts of the world. Because of this fact, military assets must present superior physical obstacles against hostile actions. Throwing large numbers of personnel at the problem is not feasible in the long term. Technology provides a better and, going forward, a more cost-efficient means of protecting our military assets. Perimeter security for these assets will continue to rely on the defense-in-depth philosophy (previously discussed under the nuclear heading) in which concentric security barriers and buffer zones both aid detection of a breach and delay an attack. This allows time for a sufficiently equipped response force to react to the threat. The most effective and reliable intrusion detection systems use multiple technologies to increase the probability of early detection under a broad range of conditions.