Awave of bombings in Nigeria has highlighted the fissures that threaten to fracture Africa's most populous nation. The violence has been launched by an Islamic militia, but it has inflamed already widespread economic and political discontent. President Goodluck Jonathan has called for a security crackdown, but it will take far more than officers on the street and enhanced authority to dampen the grievances that could tear his country apart.

On Jan. 20, a string of bombings across the country claimed more than 150 lives. Most took place in Kano, the economic capital of Nigeria's north, a region that is poor and dominated by Muslims. Another explosion in another state killed at least 11 people. These are the latest in a series of terrorist attacks ranging back at least 18 months.

Boko Haram, a Nigerian Islamic militia, took responsibility for the attacks in Kano, which were intended, among other things, to free some group members taken prisoner by the government. The group has called for the "cleansing" of Nigeria's northeast of Christians, who are the majority in the south.