Summarize in one sentence

Once these disparate parts were held together by a common enemy, by the fault lines of
world wars and the electrified fence of communism. With the end of the cold war there was the
creeping concern that without a focus for hatred and distrust, a sense of national identity would
evaporate, that the left side of the hyphen - African-American, Mexican-American, Irish-American-
would overwhelm the right. And slow-growing domestic traumas like economic unrest and
increasing crime seemed more likely to emphasize division than community. Today the citizens of
the United States have come together once more because of armed conflict and enemy attack.
Terrorism has led to devastation - and unity.