Making war has been one of the most persistent of human activities in the 80 centuries since men and women settled in cities and became thereby “civilized.” In premodernized societies, successful warfare brought significant material rewards, the most obvious of which were the stored wealth of the defeated. But the modernization of the past 80 years has fundamentally changed the role and function of war. 　　War has escaped the battlefield and now can, with modern guidance systems on missiles, touch virtually every square yard of the earth's surface. It no longer involves only the military profession but also engulfs entire civilian populations. Nuclear weapons have made major war unthinkable. We are forced, however, to think about the unthinkable because a thermonuclear war could come by accident or miscalculation. We must accept the paradox of maintaining a capacity to fight such a war so that we will never have to do so. 　　War has also lost most of its utility in achieving the traditional goals of conflict. Control of territory carries with it the obligation to provide subject peoples certain administrative, health, education, and other social services: such obligations far out-weigh the benefits of control. If the ruled population is ethnically or racially different from the rulers, tensions and chronic unrest often exist that further reduce the benefits and increase the costs of domination. 　　Large populations no longer necessarily enhance state power and, in the absence of high levels of economic development, can impose severe burdens on  food supply, jobs, and the broad range of services expected of modern governments. The noneconomic security reasons for the control of territory have been progressively undermined by the advances of modern technology. The benefits of forcing another nation to surrender its wealth are vastly outweighed by the benefits of persuading that nation to produce and exchange goods and services. In brief , imperialism no longer pays.