"Fourth-generation warfare, which is now playing out in Iraq and Afghanistan, is a modern form of insurgency. Its practitioners seek to convince enemy political leaders that their strategic goals are either unachievable or too costly for the perceived benefit. The fundamental precept is that superior political will, when properly employed, can defeat greater economic and military power. Because it is organized to ensure political rather than military success, this type of warfare is difficult to defeat. Strategically, fourth-generation warfare remains focused on changing the minds of decisionmakers. Politically, it involves transnational, national, and subnational organizations and networks. Operationally, it uses different messages for different audiences, all of which focus on breaking an opponent's political will. Tactically, it utilizes materials present in the society under attack-- to include industrial chemicals, liquefied natural gas, or fertilizers. Although these modern insurgencies are the only type of war that the United States has lost (Vietnam, Lebanon, and Somalia), they can be overcome--witness Malaya (1950s), Oman (1970s), and El Salvador (1980s). Winning, however, requires coherent, patient action that encompasses the full range of political, economic, social, and military activities. The United States cannot force its opponents to fight the short, high-technology wars it easily dominates. Instead, the Nation must learn to fight fourth-generation wars anew."
Strategic Forum (January 2005), no.214
National Defense University, Institute for National Strategic Studies: http://www.ndu.edu/inss