Part of the perplexity of strategic thought in the early 21st century stemmed from a restricted historical imagination. For most politicians and generals in the 19th and 20th centuries, war meant the kind of conflict characteristic of European contests from the middle of the 17th century to their own time: state-centred, conducted by increasingly professional armed forces, nominally excluding civilians, and involving well-defined instruments commonly available in developed states. These were wars that began with declarations and ended with armistices or treaties; they might last weeks, months, or even years, but they had definite beginnings and endings.

In the emerging world of the 21st century, it seemed reasonable to reach further back in time. Medieval warfare, after all, could last decades, even centuries. It involved states and trans- or substate organizations—even philanthropic organizations. Religion provided powerful motivation, but so too did state and even personal interest. High politics mixed with banditry, and even the most powerful persons and societies were subject to acts of extraordinary savagery and cruelty. No prudent political leader in the United States could publicly describe that country’s war with al-Qaeda as a “crusade,” but a thoughtful military historian would point to the parallels.

In such a world the classical paradigm, however modified, still holds some value. If one understands politics broadly enough—as the way in which human societies rule themselves, define and administer justice, and articulate their visions of what is possible and good—war remains very much about politics. The logic of struggle between interacting entities remains. It accounts for the possibility of surprise that forms so large an element in war. The fact that violence, however used, engages the emotions and thereby influences (and sometimes overwhelms) judgment remains true. The advent of weapons that can obliterate cities, and that may be available to small groups of terrorists and not just states, may make the stakes of strategy higher, but they were enormous in the great World Wars of the 20th century.

Strategy is a discipline of thought as well as a practical art. As strategy has become ever more complex, its dependence on a wide array of allied disciplines has grown. In the modern world the good strategist must understand something about development economics and bioengineering, as well as precision guidance and computer programming. In strategy more than other practical fields, there has long existed a craving for dicta and aphorisms: “the offense needs an advantage of three to one,” for example. Such aphorisms may never have been terribly useful, but in a new and no less dangerous century they are less helpful than ever in steering politician and soldier alike through choices that remain as consequential as they have ever been.

Eliot A. Cohen

National Security Strategy Report, annual report made by the president of the United States to Congress describing the national security goals of the United States and the strategies used to accomplish those goals. The report, which is prepared by the National Security Council (NSC), examines issues that shape national security policy, including U.S. foreign policy, military and security commitments overseas, and current national defense capabilities. It also features proposals for the short- and long-term use of political, economic, and military power to promote U.S. interests.

Section 108 of the National Security Act of 1947 calls for the president to submit a comprehensive report on the national security strategy of the United States to Congress every year. A newly elected president must submit the report within 150 days of taking office. The report is submitted in two forms: a classified version for officials with high security clearances and an unclassified version available to the public.

The first National Security Strategy Report was presented to Congress by President Harry S. Truman in 1950. Truman’s report focused on the growing rivalry between the United States and the Soviet Union since the end of World War II. It outlined the doctrine of containment—the worldwide use of American political and military power to resist the spread of communism—that dominated U.S. foreign policy during the Cold War era. Each president since that time has submitted reports that have reflected the most-pressing national security issues of the day and have indicated the direction of national security policy.

Despite its primary focus on armed threats, the national security strategy report may also outline diplomatic and economic policies meant to foster cooperation with allied countries and international organizations and to defuse conflicts. Those aspects of the report reflect the belief that providing effective national security depends as much on addressing economic and social challenges as it does on meeting military threats.

John Haley The Editors of Encyclopaedia Britannica