Nigeria declares war against jihadist militants of armed group Boko Haram 1605131.

The offensive began on Wednesday, one day after President Goodluck Jonathan issued a state of emergency in the northeast that permits soldiers to round up suspected insurgents. The military suggested the operation was intended to "put an end to insurgent activities in these parts of the country."

According to Reuters, officials say militants control at least 10 government areas in the state of Borno, where fighters overran the town of Bama last week, freeing more than 100 prisoners and killing at least 55 people. A few days before that, dozens of people reportedly died in the town of Baga, on Lake Chad. Nigerian troops, aided by troops from Niger and Chad burst into the town looking for guerrillas.

Maj. Gen. Sarkin Yaki Bello, who leads Nigeria's military campaign against Boko Haram, has sketched out a strategy on how Nigeria might expand its fight beyond military measures—including through legal means.

The militants have forged closer links with al-Qaeda-linked militants in the Sahara region and have access to increasingly sophisticated weaponry. They are believed to move back and forth across frontiers, particularly the Cameroon border, say analysts.