During a video released on March 7, Boko Haram leader Abubakar Shekau formally swore an oath of allegiance to the so-called Islamic State (ISIS). In his pledge, also known as “bayat,” Shekau publicly accepted the authority of ISIS leader Abu Bakr al-Baghdadi and vowed to support him in times of “difficulty and prosperity.” Shekau further called upon “Muslims everywhere to pledge allegiance to the Caliph and support him.” On March 12, ISIS spokesman Mohammed al-Adani graciously accepted Shekau’s oath of fealty in an audiotape recording.

This is significant in that it has the potential to formalize a relationship between two of the deadliest Islamist extremist organizations currently in operation. According to the International Centre for the Study of Radicalisation, Boko Haram and ISIS together accounted for more than 60 percent of all deaths attributed to Islamist extremism in 2014. Moreover, while it may not be the first group to ally with ISIS—with allegiances already pledged from jihadist groups in Pakistan, Libya, Egypt, and Algeria—Boko Haram is certainly the largest. According to United States intelligence officials, it has 4,000 to 6,000 core fighters, making it several times larger than ISIS’s largest-known affiliates in Egypt (Wilayat Sinai) and Libya (Wilayat al-Barqah, Wilayat al-Tarabulus, and Wilayat al-Fizan).

For many analysts, Boko Haram’s announcement comes as no surprise. In a December 2014 briefing, Jamestown Foundation analyst Jacob Zenn presented compelling evidence of Boko Haram shifting almost completely into ISIS’s orbit. In particular, Zenn noted Boko Haram was increasingly using ISIS imagery in its video communiques, such as incorporating the rayat al-uqab (the black standard or banner) flag as part of its own logo. Boko Haram’s use of Islamic chants or “nasheeds,” and the inclusion of an al-Baghdadi sermon in its videos, was seen as further evidence of an ideological, and potentially operational, contiguity with ISIS.

Suggestions of growing symbiosis gained further traction in January 2015 when Boko Haram launched its al-‘Urwah al-Wuthqa media wing, whose videos bore the sleek production quality and graphics associated with ISIS—a significant improvement on previous Boko Haram videos. Moreover, as highlighted by Jihadology founder Aaron Y. Zelin, releases from Boko Haram’s media wing were being disseminated by official and semi-official ISIS social media accounts. This, Zelin correctly predicted, was a precursor to a more formal relationship.

But, if Boko Haram had already established ties with ISIS in 2014, why has the group only offered its allegiance now? A possible explanation is that ISIS may not have previously been ready to accept Boko Haram as an official franchise. Although it espouses a similar brand of religious ideology, the Nigerian sect has lacked the credentials of the quintessential Salafi-jihadist movement. For one, unlike many of its counterparts, it has failed to attract the endorsement of any notable religious scholars within or outside of Nigeria’s borders. Equally conspicuous is the fact that the global jihadist community has never attempted to justify or even condone the group’s armed campaign.

Boko Haram’s massacring of civilian populations in northeastern Nigeria may have also prevented formalized ties with ISIS. Although it is equally brutal, ISIS has been methodical in its use of violence, generally framing it as retributive and/or justifiable under Sharia Law. Moreover, ISIS has been able to offset its violent characterization by establishing legitimate administration structures in areas assimilated into its supposed caliphate. By comparison, Boko Haram appears to be both gratuitous and explicit in its use of violence. As noted by David Cook of the James Baker III Institute for Public Policy, Boko Haram’s mass killings, pillaging, and enslavement of children more closely match the operations of an African guerrilla movement than those of a Salafi-jihadist organization.

Since purportedly establishing links with ISIS in 2014, Boko Haram has, however, made considerable efforts to transform its image. Recent communiques have offered justification for its attacks on civilian communities and refuted claims its members were indiscriminately killing Muslims. Self-proclaimed Boko Haram spokesman Sheikh Abu Mus’ab al-Barnawi showed an uncharacteristic piousness when he noted that anyone “who comes repenting will be forgiven and we will give him safety and security because we are a nation whose morals refuse us initiating harm on those who don’t harm us.”

Also worth noting is the concerted effort to alter the depiction of Shekau. The normally erratic Boko Haram leader has appeared more composed in recent video messages and has increasingly assumed the role of the sect’s spiritual leader or imam—a ploy possibly aimed at increasing his legitimacy within the jihadist fraternity. Ever cognizant of its public image, ISIS may have delayed an open alliance with Boko Haram until the group asserted itself as a more traditional Salafi-jihadist movement. The transformative process may even have been spearheaded by ISIS and its savvy public relations wing.

Another plausible explanation for the timing of Boko Haram’s declaration may relate to its composition. Although Boko Haram is often described as a homogenous entity, many analysts have argued it functions more as an umbrella organization composed of various factions. The International Crisis Group has noted that Boko Haram may have as many as six of these factions, the largest and most powerful of which falls under the direct command of Shekau. That hypothesis was echoed by Jacob Zenn in a briefing to West Point’s Combating Terrorism Center.

For its part, ISIS seemed to have doubts about the homogeneity of Boko Haram and the Nigerian jihadist movement as a whole as recently as last year. In the November 2014 edition of its official online magazine Dabiq, it noted it had accepted bayat from a number of foreign groups, including those based in Nigeria, but the declaration of an ISIS wilayat, or province, in these areas was delayed due to the presence of stronger and larger groups which had yet to submit to the authority of the caliph. The subsequent formalizing of the alliance may therefore represent enhanced synergy and coordination within Boko Haram.

The pertinent question now is how the declaration could benefit either group, if at all. To begin with, it is clear that a formal alliance could be of significant symbolic and even strategic value to both. For ISIS, declaring a “province” in Africa’s most populous country will further perceptions it is on course to achieve its raison d’être—creating a unified Islamic State spanning the Muslim world. Accepting Boko Haram as an ideological proxy also gives it an important foothold in a region where prevailing social, political, and economic conditions are conducive to religious radicalization. This could either funnel combatants to its operational core or aid it in its peripheral expansion. Furthermore, by announcing its arrival in West Africa, after already establishing a footprint north of the Sahara, ISIS is making further inroads into jihadist theaters long dominated by its ideological nemesis al-Qaeda.

Falling under the ISIS banner could also be beneficial for Boko Haram. It could broaden its appeal and potentially aid its recruitment. It could also help forge new, or entrench existing, linkages with ISIS’s Maghreb-based affiliates. Although this may not necessarily translate into operational coordination between the groups—with each very much focused on its own domestic agenda—an exchange of tactics, expertise, and resources cannot be entirely discounted.

But the pledge of allegiance does not come without risk for Boko Haram. It may have changed its outward perception from an inherently grassroots, Nigeria-focused organization to one with much wider ambitions. This could elicit a more intensive response from foreign governments. Although it is unlikely to mirror the scale of Western-backed efforts against ISIS, an internationalization of the military response to Boko Haram cannot be ruled out. France, which probably has the most to lose if Boko Haram expands into francophone Africa, could look to expand its counterterrorism campaign Operation Barkhane, headquartered in the Chadian capital of N’Djamena, to northeastern Nigeria. This could in turn be welcomed by Nigerian President Goodluck Jonathan, who touted Boko Haram as a regional threat during a May 2014 security summit in Paris.

There is still much shrouded in mystery around the new alliance. However, those anticipating an immediate and visible change in direction for Boko Haram are likely to be proved wrong. Aaron Y. Zelin, again, provides valuable insight, pointing out that ISIS’s main priority is “building out its caliphate.” It merely calls upon its affiliates to fight locally, institute local governance, and expand its operational reach—mandates which Boko Haram had already been brutally executing prior to making its pledge to ISIS explicit. Consequently, a discernible shift in the group’s strategy should not be expected.