Reduced instruction set computing, the first prototype system for which (the 801 Minicomputer at IBM Research) had as its application objective a telephone switching system; Satellite communications and the entertainment industry spawned by Telstar, which today are much broader in scope than the point-to-point communications Telstar was built for and were made possible by the initial investment in a single application; Coding and information theory, developed for data compression and error-correction, which has also found application in diverse areas such as cryptography, probability theory, biology, and investment theory. Of course, that such spin-offs occurred reflects in no small part the significant investment in long-term research that was made in the Bell system era. These and other spin-offs also demonstrate that making major advances in telecommunications requires the solution of technical problems across the spectrum from theory to device physics to software, yielding results that can have broad utility. Research in commercial and defense applications of telecommunications has contributed significantly to U.S. military strength. Captured in the phrase “network-centric warfare,” the central and growing importance of communications systems to national defense and homeland security makes these key areas that rely on having a strong U.S. research and skill base. The intensity of the communications demands that can arise in defense applications is evident in the concept of the future battlefield as being totally dependent on communications: from the fiber-optic cores of military networks to the satellite systems that provide long-reach communications to the tactical radios carried by soldiers on the battlefield. Some of these requirements are fulfilled via commercial off-the-shelf (COTS) products. Use of COTS products is often highly desirable as a means of reducing the cost of infrastructure, yet such products bring concerns as well (see the discussion below in the section “Leadership for National Defense and Homeland Security”). For example, military requirements can exceed what COTS products alone can deliver, perhaps because the demands (e.g., the need for multilevel security) are higher or the application environment is different, because of the presence of an adversary, for instance. In addition to emphasizing the impact of U.S. communications research on C4I (i.e., command, control, communications, computers, and intelligence2), it is also important to briefly note the relevance to C4I of the engineering disciplines. Much of the basic mathematics that underlies telecommunications engineering is also relevant to command and control systems. Almost any computing device depends heavily on communications technology, both internally to communicate between subelements of the computer and externally to communicate with other devices. And the field of intelligence is replete with examples of reliance on telecommunications. Hence, telecommunications research is significant for and integral to the capability and capacity of many aspects of the overall defense system.