A wall painted by Boko Haram is seen in the northern Nigerian town of Damasak on Tuesday. The group has adopted the black banner used by the Islamic State and other Islamic extremist movements, placing the flag in captured territory. (Joe Penney/Reuters)

On Feb. 25, Boko Haram formally swore an oath of allegiance, or bayat, to the Islamic State, declaring “we announce our allegiance to the Caliph of the Muslims … and will hear and obey in times of difficulty and prosperity.” Through the acquisition of territory, adept use of social media and the pioneering of grisly tactics such as the mass beheading of captives and the enslavement of women and children, Boko Haram and the Islamic State have established themselves as the vanguard of a new, savage form of irregular warfare.

Though material ties between the two groups are a major source of speculation, the widespread media coverage devoted to both groups has given each the opportunity to informally learn from and adopt one another’s tactics. The Islamic State is a clear impetus for Boko Haram’s evolution into a media-savvy, territory-seeking movement. Boko Haram’s brutal practices such as taped beheadings of captives as well as kidnappings and enslavement of women and girls predated – and perhaps inspired – the Islamic State. Though Boko Haram has benefited more, a mutual influence is undeniable and marks a troubling new chapter in the evolution of jihadist insurgency.

Disregarding international borders

Since its creation under Abu Bakr al-Baghdadi in April 2013, the Islamic State served as inspiration for Boko Haram. Reuniting two related rebel movements in Iraq and Syria, the Islamic State immediately went on the offensive and made rapid territorial gains. It expanded strongholds in northern Syria before claiming control over the Iraqi cities of Fallujah and Mosul in January 2014.  On June 29, 2014, the Islamic State formally declared itself a global caliphate.

Boko Haram was a largely urban-based insurgency under pressure when the Islamic State was founded. The Nigerian government’s declaration of a state of emergency and subsequent military offensive restricted Boko Haram’s ability to attack the northern cities of Damataru and Maiduguri. Boko Haram responded by shifting focus from urban centers to actively acquiring territory. By mid-2014, Boko Haram established significant territorial control in the far north of Nigeria along the Chad/Cameroon border and mounted sustained attacks on medium-sized towns, including Bama and Gwoza.

If Boko Haram’s sudden desire for territory in 2013 seemed to some analysts a coincidental and tactically convenient shift, the group’s declaration of a West African caliphate a mere two months after the Islamic State’s declaration left little doubt from whom Boko Haram took its inspiration. By 2015, Boko Haram was, like its cosmopolitan counterpart, disavowing international borders and seizing territory beyond Nigeria in neighboring Chad, Cameroon and Niger.

Social media mimicry

Perhaps Boko Haram’s most striking shift over the past year has been the launch of a social media and propaganda campaign highly resembling that of the Islamic State. Recent Boko Haram videos use a similar media platform and the same camera angles, and adopt the Islamic State’s music and songs. Boko Haram has even taken to mimicking grisly details like the knives it uses to behead captives.

Mirroring the shift in media, Boko Haram has begun adopting rhetoric and symbols used by the Islamic State. Before, Boko Haram’s rhetoric was mostly local and filled with grievances against the Nigerian government, but in recent videos, Boko Haram has proclaimed international jihad and called out Chad, Cameroon, Niger, the United Nations, Europe and the United States. The group has adopted the black banner used by the Islamic State and other Islamic extremist movements, placing the flag in captured territory.

Macabre tactics

In July and August 2014, the Islamic State received widespread media attention after releasing horrific videos of the beheadings of foreign captives and the Syrian military. Shortly thereafter, Boko Haram released its own beheading videos. The timing and production quality of the videos has caused most analysts to read Boko Haram’s videos as further evidence of its adoption of Islamic State-style tactics.

But is it? Boko Haram released at least two beheading videos for local media consumption in 2010 and again in February 2014, six months prior to the Islamic State’s first video.

While it is difficult to know whether the Islamic State decided independently to publicly behead its captives, there exists more direct evidence of Boko Haram’s influence on the Islamic State. One of Boko Haram’s most notorious actions has been its April 2014 kidnapping and subsequent enslavement of over 200 girls from a school in Chibok, Borno State. Beginning in August 2014, the Islamic State took captive or sold into sex slavery as many as 7,000 women from the Yazidi religious group, explicitly referencing Boko Haram’s actions in Chibok as justification.

A consolidation of the jihadist public sphere

It is unlikely anyone will be able to quantify how much the mutual influence between Boko Haram and the Islamic State is a product of direct communication and exchange of material resources. But that may not matter. Formal relations are neither a necessary nor sufficient condition for evolutions in strategy, propaganda and tactics. Prior to their official union, the Islamic State and Boko Haram were the world’s two largest jihadist movements, each commanding international media attention. It is hardly surprising that each mimicked the best practices of the other.

Social scientists use “snowball effect” or “demonstration effect” to describe how rapid change often results from social movements adopting one another’s innovations. The term has been applied to communist movements to describe the “domino” effect during the Cold War, and more recently, to the waves of democratization that have occurred since. Underpinning the success of such movements is the creation of a public sphere where members can openly discuss and identify barriers to collective action.

Boko Haram and the Islamic State owe their success to their ability to innovate, and their innovations have mutually influenced one another. In attempting to erase borders, recruit via social media, and create public spectacles out of atrocities, the groups’ leaders have built the two most destructive Islamic insurgent groups now in existence. Though Boko Haram’s swearing of allegiance to the Islamic State may have little meaning for either group’s day-to-day operations, the joining of the two groups represents a troubling new chapter in the formation of a truly international jihadist public sphere.

Nathaniel D.F. Allen is a PhD candidate at the Johns Hopkins School of International Studies (SAIS) in the District, where he focuses on the politics of insurgency, civil-military relations, foreign aid and development in Africa. He is a researcher with SAIS’s Nigeria Social Violence Project.