WASHINGTON — Until recently, the propaganda videos released by Boko Haram, one of the most feared extremist groups in Africa, were an amateur affair. The videos were grainy, shot on hand-held cameras. They tended to feature the group’s wild-eyed leader screaming or shaking his finger at the viewer, as he delivered an incoherent tirade.
That all changed in January, when Boko Haram announced that it had created its own media outlet, with its own logo, and unveiled an associated Twitter account. What followed was a barrage of videos and photographs, mirroring the releases of the Islamic State terrorist group thousands of miles away in Iraq and Syria. The videos were suddenly more polished, shot by what analysts say was a professional cameraman, and branded with the flag of the Islamic State, also known as ISIS or ISIL, as well as the group’s battle anthem.
Since then, each clip has surfaced first on the Nigerian group’s Twitter account and is then promulgated on accounts known to belong to Islamic State operatives, according to three experts who track jihadist activity online.
This evolution comes months after the Islamic State announced in its official magazine, Dabiq, that it had received an oath of allegiance from a group in Nigeria. Though the Islamic State did not name Boko Haram, the combined sequence of events has caused several experts to question whether Boko Haram is on its way to becoming the official branch in Nigeria, creating an alliance between two of the world’s most murderous groups.
“The media, the optics, the graphics, the style of these videos, as well as who is pushing this content out amounts to a lot of smoke,” said Aaron Zelin, a senior fellow for the Washington Institute for Near East Policy who maintains a database of jihadist statements and videos. “I’m uncertain if there is a fire yet, but there seems to be a lot of circumstantial evidence pointing to a link between Boko Haram and ISIS.”
It remains too early to draw conclusions, and intelligence analysts in the United States remain unconvinced.
“Despite recent Boko Haram media releases that suggest support for ISIL and the claim in Dabiq magazine, Boko Haram has not pledged allegiance to ISIL,” said James M. Kudla, a spokesman for the Defense Intelligence Agency. “Regarding video production values, although Boko Haram media production progressed during the past year, it is unclear how the new capabilities were developed.”
Another American official, who spoke on the condition of anonymity to discuss confidential information, said, “The pledges and even the Twitter accounts probably do not signify a deeper connection.”
He likened the actions to someone “liking” an individual or group on Facebook.
At the same time, experts who track the Islamic State say the sequence of events follows an established pattern by which jihadist groups who share the Islamic State ideology are brought into the fold. The terrorist group’s other main franchises, in Egypt and Libya, were first recognized as affiliates in Dabiq last year. Once they were accepted as branches of the Islamic State, their releases to news organizations became more polished.
The news releases of the Libyan affiliate have become so professional and similar to those of the Islamic State that some terror experts suggest that the Islamic State must have dispatched its own cameraman to Libya to give media training to the fighters there and to help them shoot a video, released this week, of the mass beheading of a group of Egyptian Christians.
The shift in the look of Boko Haram’s videos and photographs began last summer, after the group’s leader, Abubakar Shekau, issued a statement praising the Islamic State leader, Abu Bakr al-Baghdadi, said Jacob Zenn, an analyst on African affairs for the Jamestown Foundation.
“Immediately after you started to see signs of them mimicking ISIS choreography,” he said. “If ISIS issued a video showing a convoy of cars going by, flying the black flag, Boko Haram released a video of cars flying the black flag.”
Previously, Boko Haram videos had been almost comically inept, including one where Mr. Shekau interrupts his lengthy sermon to scratch his crotch.
Now the militants appear to be taking greater care to edit their videos. While their most recent ones are still a far cry from the Hollywoodesque montages put out by the Islamic State, they are noticeably slicker than before.
The biggest clue to a growing synergy between the groups, however, is the fact that known Islamic State members are now among the first to repost Boko Haram releases that appear on Twitter, said J. M. Berger, the co-author of “ISIS: The State of Terror.”
“There is a relatively robust group of ISIS media workers who are generally the channels through which stuff comes out,” said Mr. Berger, a resident fellow at the Brookings Institution. “And Boko Haram videos are now being promulgated by them.”
However, scholars of Boko Haram point to the group’s lack of a clear, central command as a barrier to any alleged allegiance to another terrorist group.
Marc-Antoine Pérouse de Montclos, the author of a recent report on the Nigerian group by the Chatham House research organization in London, calls Boko Haram “very fragmented, not centralized.” And since Boko Haram was created nearly six years ago, its targets, goals and public declarations have remained almost exclusively Nigerian.
“The sect is still a local problem,” Mr. Pérouse de Montclos wrote in his report.