Just over a year ago, Congolese troops found a book written in Arabic on the body of an enemy combatant.
The book was from the Islamic State’s Research and Studies Office, a department of the terrorist group’s now-defunct state in Syria and Iraq that issued doctrinal texts buttressing its brutal worldview. The discovery of the book in the spring of 2018 was among a number of clues indicating that the Islamic State, also known as ISIS, was trying to establish a toehold in the lawless jungles of eastern Congo.
On Thursday, the Islamic State’s news agency claimed the group’s first attack in the Democratic Republic of Congo, stating that its soldiers had assaulted a military barracks in the area of Beni, killing eight people.
The attack took place in a region beset by violence in a part of the world long outside government control, the kind of terrain that has proved to be fertile ground for ISIS. If the group succeeds in planting its flag here, it would not only expand its reach into a new part of the continent, but it would also do so far outside the grasp of international forces.
Congolese officials confirmed that an attack on a small military unit had occurred there days earlier, but they said the assailants belonged to the Allied Democratic Forces, a rebel group that originated in neighboring Uganda and is accused of killing hundreds of people over the past three years.
While the Allied Democratic Forces, or A.D.F., is an established rebel group with a decades-long history in the area, documentation collected by the Congo Research Group, an independent nonprofit run by a leading scholar of the country’s successive conflicts, shows that the militants have not only been espousing jihadist ideology but have also been receiving funds from ISIS operatives.
Laren Poole, a co-author of the Congo Research Group report, said interviews with A.D.F. defectors showed that the rebels had received cash transfers from Waleed Ahmed Zein, a Kenyan national who was identified as an ISIS financial facilitator by the United States Treasury Department.
“We have been able to track the finances, down to bank accounts and receipts showing money moving from Britain, South Africa and Syria via Zein, through Uganda and into A.D.F. hands,” said Mr. Poole, adding, “It’s not a lax connection.”
In a statement, Maj. Karl J. Wiest, a spokesman for the United States Africa Command, said that the group in Congo is considered to have “meaningful ties to the Islamic State.”
Other signs of a link to ISIS can be found in 35 videos that one A.D.F. member posted online starting in 2016.
The footage shows the rebel group’s flag, which includes the so-called “seal of Muhammad,” the main visual element of the ISIS banner. Interviews with defectors indicate that the flag was seen flying from camps run by the combatants in eastern Congo, Mr. Poole said.
One video shows a man explaining that the group intends to create an Islamic State in Congo and calling on others to join them.
The message appears to be working, according to Mr. Poole, who said the recruitment drive appealed especially to Islamists in the region who could not afford a plane ticket to the Middle East and instead could head to Congo for the equivalent of a $20 bus ticket.
“In the last year, we have debriefed a South African, a Tanzanian, a Kenyan, a Rwandan, a Burundian, a Brit and a South Sudanese,” he said. “That’s a very worrying trend for an area that has been rocked by violence.”
While the evidence points to a concrete connection with the Islamic State, that does not mean the international terrorist group has a viable franchise in Congo. It remains unclear to what extent the A.D.F. is in communication with ISIS, or whether it is also flirting with other jihadist groups, including Al Qaeda.
However, the manner in which the affiliation appears to have been forged fits a pattern.
In many areas where ISIS has developed active chapters — from the coast of Libya to the deserts of Sinai in Egypt, to safe houses in Bangladesh — the has grafted itself onto existing militant groups.
“ISIS is basically co-opting a group in Congo that has been carrying out atrocities against civilians for some time,” said Mr. Poole.
Among the data points that indicate a link to ISIS in eastern Congo is the claim that the recent attack was carried out under the banner of the “Central Africa Wilayat.” According to the Islamic State’s own literature, the religious empire it calls a caliphate is divided into 35 “wilayats” or provinces, 16 of which are outside Iraq and Syria.
While the recent attack is the first to be claimed for this newly minted province, it isn’t the first time the province has been mentioned.
In one of his rare audio recordings, released in 2018, the ISIS leader Abu Bakr al-Baghdadi made a passing reference to a Central African province, suggesting that the geographic subdivision had existed in the terror group’s own nomenclature as far back as last year.
One of the most tantalizing clues is the discovery of the hard-bound book published by the Islamic State department dedicated to articulating its ideology.
Congolese troops recovered it last year from the corpse of an A.D.F. combatant, said Mr. Poole. Another copy of the same book was discovered by a team of Times reporters in the Iraqi city of Mosul, in a building formerly occupied by the Islamic State’s suicide bomber squad.
First issued in late 2014, the book provides an overview of how the Islamic State is supposed to be run and acts as a primer for those trying to establish a new territory under the group’s aegis, said Cole Bunzel, a research fellow in Islamic law and civilization at Yale Law School.
“The physical aspect is super interesting,” said Caleb Weiss, a research analyst who wrote about the Islamic State’s expansion into Congo for the Foundation for Defense of Democracies’ Long War Journal. “We don’t know if they published the book themselves, or if it was brought there, in which case it had to move through several countries to get to the Democratic Republic of Congo.”