that fight will take place in the shadows. It will be the work of intelligence operatives, paramilitary groups, and Special Operations forces. It will also require close relationships with other governments and local forces. The next U.S. president should direct our armed forces to emphasize such work, in part because local forces are best able to operate in their home countries and in part in order to reduce the strain on our own troops.A STRONGER DEFENSEFor 15 years, the de facto policy of both Republicans and Democrats has been to ask the U.S. military to do increasingly more with increasingly less. The idea of a post-Cold War "peace dividend" was a serious mistake -- the product of wishful thinking and the opposite of true realism. As a result of taking this dividend, our military is too small to meet its current commitments or shoulder the burden of any additional challenges that might arise. We must rebuild a military force that can deter aggression and meet the wide variety of present and future challenges. When America appears bogged down and unready to face aggressors, it invites conflict. The U.S. Army needs a minimum of ten new combat brigades. It may need more, but this is an appropriate baseline increase while we reevaluate our strategies and resources. We must also take a hard look at other requirements, especially in terms of submarines, modern long-range bombers, and in-flight refueling tankers. Rebuilding will not be cheap, but it is necessary. And the benefits will outweigh the costs.The next U.S. president must also press ahead with building a national missile defense system. America can no longer rely on Cold War doctrines such as "mutual assured destruction" in the face of threats from hostile, unstable regimes. Nor can it ignore the possibility of nuclear blackmail. Rogue regimes that know they can threaten America, our allies, and our interests with ballistic missiles will behave more aggressively, including by increasing their support for terrorists. On the other hand, the knowledge that America and our allies could intercept and destroy incoming missiles would not only make blackmail less likely but also decrease the appeal of ballistic missile programs and so help to slow their development and proliferation. It is well within our capability to field a layered missile defense capable of shielding us from the arsenals of the world's most dangerous states. President George W. Bush deserves credit for changing America's course on this issue. But progress needs to be accelerated.An even greater danger is the possibility of a terrorist attack on U.S. soil with a chemical, biological, radiological, or nuclear weapon. Every effort must be made to improve our intelligence capabilities and technological capacities to prevent this. Constellations of satellites that can watch arms factories everywhere around the globe, day and night, above- and belowground, combined with more robust human intelligence, must be part of America's arsenal. The laudable and effective Proliferation Security Initiative, a global effort to stop the shipment of weapons of mass destruction and related materials, should be expanded and strengthened. In particular, we must work to