Islamic State Welcomes Boko Haram 'Brothers'

The Islamic State has officially accepted Boko Haram's pledge of allegiance. The joining of the two Islamic terror groups has been in the works since last week.

First, the leader of Boko Haram pledged allegiance to the Islamic State through an audio recording.

Then on Thursday, ISIS leaders made it official in a video statement released by the terror group's media arm, al-Furqan.

"I proclaim to you today the expansion of the Caliphate to West Africa," ISIS spokesman Abu Mohammed al-Adnani says in the video. "The Caliph, may God protect him, has accepted the sworn allegiance of the Sunni brothers' call for the Jihad."

"We congratulate our Muslim and Mujahedeen brothers in West Africa for their allegiance," he said.

The Islamic State seized much of northern and western Iraq last summer.  But it is now struggling against Iraqi and Kurdish forces.

Meanwhile in West Africa, Boko Haram has been weakened by a multinational force that's dislodged it from a score of northeastern Nigerian towns.