PORT HARCOURT, Nigeria -- On Oct. 2, Nigeria celebrated the 51st anniversary of its freedom from British rule. A large gala was planned in Abuja, the fast-growing Nigerian capital located in the center of the country.

But, days before the celebrations, Boko Haram, a Muslim extremist group based in the country's north, and the Movement to Emancipate the Niger Delta (MEND), based in the country's oil-rich south, both threatened to disrupt the festivities with violence. Boko Haram had already made it clear that it was capable of attacking Abuja on Aug. 26, when it exploded a bomb at the United Nations building there, killing 23. And just a week before the scheduled gala event, a bomb scare at the country's National Assembly sent lawmakers scrambling for safety. ...