Nigeria's Boko Haram has reportedly announced formal allegiance with the self-declared Islamic State, according to an English-language translation of an Arabic message posted to Twitter.
"We announce our allegiance to the Caliph ... and will hear and obey in times of difficulty and prosperity, in hardship and ease," according to a translation of a message purporting to be by Boko Haram leader Abubakar Shekau. "We call upon Muslims everywhere to pledge allegiance to the Caliph."
It was not immediately clear if the message was a video or audio only.
The translation was provided by SITE Intelligence, an organization that monitors Islamist extremist groups.
However, NPR's Ofeibea Quist-Arcton cautions that the message has yet to be authenticated.
"The ... script identified the Caliph as Ibrahim ibn Awad ibn Ibrahim al-Awad al-Qurashi, who is better known as Abu Bakr al-Baghdadi, the leader of ISIL and self-proclaimed caliph of the Muslim world.
"Baghdadi has already accepted pledges of allegiance from other armed groups in the Middle East, Afghanistan, Pakistan and north Africa."
Ofeibea says: "Boko Haram, which is waging war against the Nigerian state, has in the past claimed links to al-Qaida. If confirmed, it would be the latest in a series of groups to swear allegiance to Islamic State."
Reuters notes that if the message should prove authentic, "[the] symbolic move highlights increased coordination between jihadi movements across north Africa and the Middle East and prompted an appeal from Nigeria's government for greater international help in tackling the Boko Haram insurgency."
In an interview with NPR earlier this week, J. Peter Pham, the director of the Atlantic Council's Africa Center, noted the "convergence" of Islamist extremist groups over the past year.
"[Not] necessarily evidence of command and control or direct coordination, but shout-outs to each other," he said.
Pham told NPR that the U.S. should be concerned with Boko Haram's flirtation with Islamic State.
"With Boko Haram, the danger is to use the past to analyze the present, much less to predict the future," he told Ofeibea. "This is a group that has shown its ability to evolve at an almost dizzying pace ... and its leadership has shown a great flexibility in ideology and methods, depending on who they choose to align with."