Islamic State seized much of northern and western Iraq last summer, gaining control of about a third of both Iraq and Syria. But it is now struggling against Iraqi forces seeking to recapture Saddam Hussein`s hometown of Tikrit, while coming under fire from U.S.-led coalition air strikes in other parts of the country and in Syria.
Boko Haram, meanwhile, has been weakened by a multinational force that has dislodged it from a score of northeastern Nigerian towns. But its new Twitter account, increasingly slick and more frequent video messages, and a new media arm all were considered signs that the group is now being helped by IS propagandists.
Then on Saturday, Boko Haram leader Abubakar Shekau posted an audio recording online that pledged allegiance to IS.
"We announce our allegiance to the Caliph of the Muslims ... and will hear and obey in times of difficulty and prosperity, in hardship and ease, and to endure being discriminated against, and not to dispute about rule with those in power, except in case of evident infidelity regarding that which there is a proof from Allah," said Boko Haram`s message.