West African states respond to insurgencies by building city walls and fortifying borders. These initiatives aimed at controlling the movement of jihadist groups are a double-edged sword. While they provide short-term protection, they can also deepen rural insecurity and civilian vulnerability.
By Olivier Walther and Steven M. Radil, 4/28/2026.
The new fortresses
In August 2024, militants from Jama’at Nusrat al-Islam wal-Muslimin (JNIM) attacked residents of Barsalogho, a town in north-central Burkina Faso, as they dug a 20-kilometer defensive trench.
The Burkinabe soldiers and self-defense volunteers guarding the construction site retreated, leaving approximately 300 unarmed civilians to be killed. It was the worst single attack in the country’s history.
Barsalogho is one site in a much larger pattern. Over the past fifteen years, West African governments, local communities, and international donors have built hundreds of kilometers of earthen fortifications to slow jihadist incursions.
Our analysis shows that sand berms up to three meters high now encircle most major towns in northeastern Nigeria and the Lake Chad basin.
Cameroon has also fortified nearly 200 kilometers of its border with Nigeria while Togo has built over 36 kilometers of defensive works along its frontier with Burkina Faso and Benin.
Whether around a town or at a border, these structures are designed to stop highly mobile fighters, to channel traffic through fortified gates, and to prevent suicide attacks.
The fortification of West African territory has few modern precedents, but it has deep historical ones. In the precolonial era, cities, villages, and individual house clusters defended themselves with earthen walls and mountain refuges against raiding and political fragmentation.
Most of these structures disappeared during the twentieth century as colonial and postcolonial states consolidated control. They are now being rebuilt.
Protecting cities
Most fortifications in the region are built around entire cities and take a circular shape, as in Kauwa, Nigeria, shown below. Their size is often considerable. The berm surrounding the city of Pama in Burkina Faso has a circumference of 15 kilometers. The one around Maiduguri, more than 65 kilometers.
Deep trenches are also built around power stations, government offices, schools, and hospitals. Even strategic crossroads are surrounded by rings of earthworks, as along the Gubio-Damasak road in northern Nigeria.
When fortifications protect military camps or forward operating bases, they are generally accompanied by bunkers and tanks and take a square shape, as in Assighassia in Cameroon below.
The primary role of these structures is to slow offensives by militants who use highly mobile vehicles such as motorcycles and pickup trucks. By forcing attackers to dismount, the defenses guard against suicide attacks, which have killed nearly 4,500 people in West Africa from 2011 to 2024, according to ACLED.
On 6 April 2022, for example, Boko Haram militants parked their motorcycles behind a trench dug around the town of Damboa in Nigeria and entered on foot, setting part of a primary healthcare center and a technical girls’ college ablaze.
Around cities, the moat dug outside the berm prevents attackers from using the barrier to take up positions with heavy weapons, particularly the machine guns mounted on light vehicles, or “technicals,” that are ubiquitous in the region.
Earthworks also allow government forces to channel traffic through a small number of fortified gates, where travelers’ identities are verified through numerous checkpoints.
Our analysis of satellite imagery shows that fifty major earthworks have been built in northeastern Nigeria and around Lake Chad.
All urban agglomerations with more than 10,000 inhabitants are surrounded by earthworks long enough to be visible on satellite images, as shown below.
The exceptions are towns abandoned following battles between the government and jihadist insurgents, such as Fage (Kirenowa), Ngurno and Abadam, or towns protected by bodies of water such as Baga Sola.
The perimeter of these fortifications is estimated at 560 kilometers. If we include the defensive trenches within urban areas as well as those built in smaller towns, the total length is likely to reach 700 kilometers, corresponding to the distance between Maiduguri, the largest city in Borno State, and the Nigerian capital of Abuja.
In many cases, several generations of walls have been built, each set further from the city center. The most imposing structures are those protecting the “super-camps” created by the Nigerian government beginning in the late 2010s to protect both its soldiers and part of the civilian population, as in Monguno below.
Because of the considerable labor involved, fortifications are generally funded by West African governments. In northeastern Nigeria, however, the United States helped fund defensive earthworks through the Office of Transition Initiatives (OTI) beginning in the mid-2010s.
The Northeast Regional Initiative (NERI), a USAID-funded program, financed trench construction around towns in Borno State as part of a set of measures designed to contain Boko Haram and the Islamic State West Africa Province (ISWAP) in the Lake Chad region.
Trenches were built by private contractors using excavators in numerous sites including Monguno, Kanamma, Damasak, Bama, Pulka, Shuwa Tomri, and Dikwa.
In an archived USAID report, the fortification efforts were described as an effective deterrent to incursions by insurgents and listed alongside streetlights and floodlights as key program outputs.
In Karetu, which lies 130 kilometers nord-west of Maiduguri, an unsuccessful insurgent attack was attributed to the trench surrounding the community. After the Nigerian military retreated from Karetu, a significant portion of the population left and public service establishments such as the health clinic were burned down by insurgents.
The ruins of the village and the trenches are still visible on the satellite images taken 6 years ago. In total, this small settlement of around 3,000 people was surrounded by 11 kilometers of trenches forming three concentric rings, as shown below.
Trenching activities were also interrupted in Magumeri and Gubio, two other villages located along the Maiduguri-Damasak highway.
Many fortified cities of northeast Nigeria seem to have followed a similar sequence of events. First, military posts stationed in rural areas are attacked from all sides by swarms of highly mobile motorcycles. This leads civilians to flee rural areas for better-protected cities.
As security forces feel increasingly vulnerable, trenches are dug as a last attempt to hold the line. When the trenches fail, the military retreats and the town is overrun by the insurgents.
Fortified borders
Cities are not the only places to be fortified. West African governments have also embarked on extensive programs to fortify their borders.
The most extensive work has been carried out by Cameroon to protect its territory from the expansion of Boko Haram and ISWAP since the mid-2010s. Our analysis shows that nearly 200 kilometers of the Cameroonian border are now fortified by trenches, as shown on the map below.
This work comprises three segments: from Golmo Kotoko near Lake Chad to Fotokol along the El Beid River, from west of Tilde Goulfey to Michidiré, and from Waza to the south of Djibrili. In the Limani region, this last segment consists of several enclosures designed to prevent any movement through the forested area south of Keroua.
The Cameroonian border trenches highlight key differences with the city enclosures of northeastern Nigeria. Border fortifications are typically linear rather than circular, designed to seal a frontier rather than protect a settled population.
They are also more likely to be state-directed projects rather than built with international donor funding. As such, border fortifications are a military infrastructure project on a scale that few other West African states have attempted.
Further west, Togo has built over 36 kilometers of trenches along its border with Burkina Faso and Benin, as the map below illustrates.
This area is almost devoid of roads but is nevertheless one of the most active regions for the JNIM katiba operating from Kompienga in Burkina Faso. On 2 October 2024, JNIM militants attacked the construction site near Kpékankandi, where the trench ends. Nine soldiers, including two Turkish military contractors, and ten civilians, most of them workers for the Burkinabè construction company EBOMAF, were killed.
The Kpékankandi attack and the Barsalogho massacre both highlight how a fortification project itself can become the target. In both cases, workers constructing the fortifications were attacked by militants that the projects were meant to stop.
The construction of defensive infrastructure, whether around cities or along borders, announces a community’s or state’s intention to restrict insurgent movement, and armed groups have, at times, treated that announcement as a provocation.
Echoes of history
The multiplication of earthworks observed in West Africa today is reminiscent of the nineteenth century, during which parts of the region were plagued by political instability.
In Central Mali, the ancient city of Jenné-Jeno, Hamdallaye’s “ideal city” in Macina, the Marka cities of the Inner Niger Delta, and a very large number of towns were surrounded by walls.
European explorers traveling through the region took careful note of these fortifications. Crossing the Bambara kingdom of Kaarta in 1805, Mungo Park noted that Mamiakoro “is a walled town fortified in the strongest manner I have yet seen in Africa.”
Twenty years later, René Caillé noted that fortifications were ubiquitous in today’s central Mali. Even the city of Djenné, built on an island of the Bani River, was surrounded by a 3-meter wall pierced by narrow gates.
Fortifications were far from being limited to major cities. Due to Fulani and Tuareg raids, many small towns and villages of western Niger were also forced to fortify themselves with mud-brick ramparts preceded by ditches. In the countryside, banditry was widespread, forcing villages to surround themselves with mud walls and fences, often made of wooden stakes or thorn bushes.
On the fringes of Sahelian kingdoms, slave raids added to political insecurity, driving pagan populations to seek refuge in mountain ranges. There they developed spectacular defensive architecture, as seen in the Piniari, the Bandiagara Cliff, the Gamdamia, or the Hombori Mountains in Mali.
A striking example is the village of Niongono, situated on a high, horseshoe-shaped plateau west of Bandiagara in Mali, as shown below. The houses were built like small forts, with limited access points, requiring visitors to navigate a maze of passageways to finally reach their home.
When the terrain offered no protection against insecurity, each cluster of houses became a small fortress, as in the Koutammakou region between northern Benin and Togo.
Some of these fortified villages and towns were destroyed by colonial powers, especially when they had military or symbolic value. In 1849, Lieutenant Bouchez, tasked with destroying the fortress built by El Hadj Omar in Dinguiraye reported that it consisted of three walls: the first was a 4-meter-high crenellated wall made of stone and mortar; the second was a 6-meter-high wall; and the third contained a parapet walk.
Most of these fortifications, however, gradually disappeared in the twentieth century. The earthen walls crumbled over the seasons, while the wooden barriers were reused by the villagers. In Gaya, Niger, the elders we interviewed still remember seeing the town’s butchers use this wood for their stoves.
After the Fulani raids disappeared, the mountain fortresses of the Dogon Country were slowly abandoned in favor of the plains. Starting in the 1980s, these perched settlements built into steep, often inaccessible, sandstone cliffs were repurposed for tourism and designated as World Heritage Sites, as were the Batammariba earthen fortresses of Koutammakou.
The conditions that produced these precolonial fortifications – fragmented political authority, mobile raiding, and the inability of any single power to secure the spaces between settlements – bear a close resemblance to the conditions prevailing in the region today.
The walls that crumbled after colonial pacification are being rebuilt because the insecurity they once compensated for has returned.
Fortifications and mobility
This history tells us that the current wave of fortification of West African cities and borders is an inevitable response to the rise in political violence in the region.
It is difficult to imagine how government forces could respond to repeated attacks by jihadist groups without fortifying major population centers and without attempting to prevent these groups from infiltrating across their borders.
However, massive investment in defensive infrastructure has pernicious consequences for both civilians and government forces.
In northeastern Nigeria, the proliferation of fortified camps has effectively given jihadist groups free rein in rural areas. Our analysis shows that Boko Haram and ISWAP have significantly increased the frequency of their attacks since the government retreated to its fortified positions in the late 2010s.
A considerable portion of the region north and east of Monguno, all the way to Lake Chad, is now devoid of its rural population. The fields lie abandoned. The thatched roofs of the villages have been burned.
The mud-brick walls are washing away with the rains, as in Koshebe, where Boko Haram massacred 110 farmers in 2020. After a few years, the trees planted by villagers before the war are the only trace of former human settlements, as in Ugurun in Nigeria today.
Bordering the Nigerien frontier, the town of Malan Fatori bears witness to this devastation. More than a decade after being captured by Boko Haram, only a handful of former residents have returned to live in the town’s ruins.
Concentrating rural populations in fortified cities rather than fortifying rural settlements also exposes communities to attack when they search for livelihoods outside the perimeter.
In March 2024, over 200 villagers were abducted by Boko Haram or ISWAP militants near Ngala, in Borno State, after they moved beyond the protective trenches in search of firewood that could not be found within the camp.
The fortified perimeter that protects residents from assault simultaneously confines them, and the resources within it are finite. People leave because they must, and when they do, they enter territory the state no longer controls.
The construction of large defensive perimeters also ties down a significant number of troops in static positions. If West African states were to deploy the same number of soldiers per kilometer of fortification as Morocco does along its 2,700-kilometer sand berm border wall with Western Sahara, nearly 30,000 soldiers would be needed to secure the perimeters identified in this study alone. The comparison is imperfect, but it suggests the scale of the commitment that effective perimeter defense requires.
More broadly, the pattern of fortification newly visible across West Africa points to the divergent geographies involved in the relationship between states and insurgent groups.
Government forces hold fixed points in towns and, in some cases, along frontiers while insurgent groups largely have free rein in the space between them.
The defensive infrastructure that protects cities and borders simultaneously announces the limits of the state’s ability to reach beyond their walls.
In this sense, the berms and trenches of northeastern Nigeria and the Lake Chad basin are not only military installations. They are the physical expressions of state sovereignty that is rapidly contracting to only the places it can materially defend.