Lawrence Summers, the dominant professor-politician of the Clinton years, used to say that the United States is history's only nonimperialist superpower. But is this claim anything to boast about today? The war on terrorism has focused attention on the chaotic states that provide profit and sanctuary to nihilist outlaws, from Sudan and Afghanistan to Sierra Leone and Somalia. When such power vacuums threatened great powers in the past, they had a ready solution: imperialism. But since World War II, that option has been ruled out. After more than two millennia of empire, orderly societies now refuse to impose their own institutions on disorderly ones.
This anti-imperialist restraint is becoming harder to sustain, however, as the disorder in poor countries grows more threatening. Civil wars have grown nastier and longer. In a study of 52 conflicts since 1960, a recent World Bank study found that wars started after 1980 lasted three times longer than those beginning in the preceding two decades. Because wars last longer, the number of countries embroiled in them is growing. And the trend toward violent disorder may prove self-sustaining, for war breeds the conditions that make fresh conflict likely. Once a nation descends into violence, its people focus on immediate survival rather than on the longer term. Saving, investment, and wealth creation taper off; government officials seek spoils for their cronies rather than designing policies that might build long-term prosperity. A cycle of poverty, instability, and violence emerges.
There is another reason why state failures may multiply. Violence and social disorder are linked to rapid population growth, and this demographic pressure shows no sign of abating. In the next
20 years, the world's population is projected to grow from around six billion to eight billion, with nearly all of the increase concentrated in poor countries. Some of the sharpest demographic stresses will be concentrated in Afghanistan, Pakistan, Saudi Arabia, Yemen, and the Palestinian territories -- all Islamic societies with powerful currents of anti-Western extremism. Only sub-Saharan Africa faces a demographic challenge even