For three years after the U.S. invasion, it seemed that Iraq had escaped one of the most pernicious effects of war - massive population displacement. No longer. The International Organization for Migration, a U.N.-affiliated aid agency, recently reported that more than 150,000 people had been displaced by sectarian violence. Virtually all are "internal refugees," and they are dispersed throughout Iraq.

The violent history of the Palestinians demonstrates the dangers of protracted refugee crises. The United Nations recognizes nearly 4 million Palestinian refugees, some of them the grandchildren of refugees who fled Israel in 1948. Over the decades, the impoverished refugees coalesced into a highly organized and militant "state" in exile. Conflict between Israeli forces and Palestinian militants has led to pitched battles in the crowded, politicized refugee camps in the West Bank and Gaza Strip. International negotiators agree that the issue of refugees is one of the most intractable barriers to a peace agreement.

A common response to a refugee crisis is to stockpile tents and food supplies. Yet in Iraq, as elsewhere, merely providing humanitarian assistance to the displaced will only entrench the refugees in their new locations. In addition to caring for the refugees, the Iraqi government must quickly return them safely home. Such a solution requires a restoration of political order in the refugees' home communities. In the race to prevent full-scale civil war, ignoring the refugees could prove a fatal misstep.