A 13-minute-long video shows fighters from both factions chanting in solidarity. Soon afterward, the Boko Haram fighters pledge their support for the newly appointed Islamic State West African Province (ISWAP) commander, known as “Khalifa Muslimai,” meaning, “The leader of all Muslims.”
A Nigerian military spokesperson was not immediately available to comment. But security expert Senator Iroegbu said a fusion of both groups could mean more lethal attacks.
"They now have the ability to consolidate their energy," Iroegbu said. "There will be consolidation of leadership, resources, intelligence, which will be more difficult for the Nigerian state to deal with. When they had two factions, you could easily infiltrate an ability to work one against the other.”
Boko Haram and ISWAP have been clashing for control of territory for many years.
Boko Haram is known to hold larger bases in northeastern Nigeria’s Borno and Adamawa states.
In May, the group's leader, Abubakar Shekau, reportedly blew up himself in order to avoid capture by ISWAP — although it must be noted that Shekau has been reported dead many times before.
Darlington Abdullahi, a retired high-ranking air force officer, said ISWAP will likely take control of more areas but said the rivalry between the groups is not over.
"They're a more tested set because they're coming from an environment where they've been at war with very strong nations," Abdullahi said. "The battle between the two groups will still continue for a while but on the whole there's more danger for the lives of people around generally.”
Abdullahi said government security forces must act without delay or there will be repercussions.
"At this stage is when all elements, all forces should be brought against them because they're still trying to find their footing and trying to get other elements of Boko Haram into their fold," Abdullahi said.
ISWAP is known for often targeting the military and easily recruiting civilians from communities. Experts fear that ISWAP's reign will make the Islamist insurgency much more difficult to control and set back years of progress.