"Always dynamic, Army doctrine balances between the Army's current capabilities and situation with its projected requirements for future operations. At the same time, Army doctrine forecasts the immediate future in terms of organizational, intellectual, and technological developments. This requirement is particularly challenging for this edition of FM 3-0 [Field Manual 3-0]. The Army is heavily committed in conflicts in Afghanistan and Iraq and to countering terrorism worldwide. How long this will remain the case remains unknown. Therefore, this edition promulgates doctrine for Army operations in those conflicts. However, America's strategic requirements remain global. FM 3-0 does not focus exclusively on current operations, regardless of how pressing their requirements. The Army's experience makes it clear that no one can accurately predict the nature, location, or duration of the next conflict. So this doctrine also addresses the needs of an Army responsible for deploying forces promptly at any time, in any environment, against any adversary. This is its expeditionary capability. Once deployed, the Army operates for extended periods across the spectrum of conflict, from stable peace through general war. This is its campaign capability. […] Despite the vital importance of nonlethal action to change the civil situation, FM 3-0 recognizes that the Army's primary purpose is deterrence, and should deterrence fail, decisively winning the Nation's wars by fighting within an interdependent joint team. America is at war and should expect to remain fully engaged for the next several decades in a persistent conflict against an enemy dedicated to U.S. defeat as a nation and eradication as a society. This conflict will be waged in an environment that is complex, multidimensional, and rooted in the human dimension. This conflict cannot be won by military forces alone; it requires close cooperation and coordination of diplomatic, informational, military, and economic efforts. Due to the human nature of the conflict, however, landpower will remain important to the military effort and essential to victory. FM 3-0 considers the nature of today's enemies as well as a wide range of other potential threats. It contains doctrine that seeks nothing less than victory for the United States--now and in the future."
Field Manual No. 3-0, Change No. 1 (FM 3-0, C1)
Federation of American Scientists (FAS): http://www.fas.org