The sudden death this week of Chad’s longtime President Idriss Deby has thrown the country, as well as its neighbours and international partners, into disarray.

The 68-year-old died after succumbing to wounds sustained while commanding troops fighting off advancing rebels who go by the name Front for Change and Concord in Chad, or FACT, according to Chad’s military.

Over the course of Deby’s three-decade hold on power, Chad has remained one of the poorest countries in Africa, but it has also come to be seen as a military linchpin in the escalating fight against armed groups in Central and West Africa.

While there are few reliable figures about the size of the Chadian armed forces (estimates put it in the tens of thousands), Chad has built a reputation for possessing the most powerful military in the G5 Sahel, an alliance also comprised of Burkina Faso, Mali, Mauritania and Niger that was created to tackle armed groups operating in the region.

Earlier this year, Chad committed 1,200 troops to the epicentre of the violence: the border zone between Niger, Mali and Burkina Faso. The deployment demonstrated Chad’s willingness and ability to commit troops beyond its own borders, something the other G5 Sahel countries have struggled to do.

On Thursday, the Burkinabe newspaper Sidwaya reported that Chadian troops with “pick-ups, tanks and personnel carriers” had been spotted leaving the Burkinabe section of the tri-border region, apparently to return to Chad. Similar reports in the days before Deby’s death had also said Chadian military units deployed abroad were being brought back to help defend Chad’s capital, N’Djamena, from FACT.

“France and the United States depended on Deby’s leadership and his military might to advance their regional security objectives,” said Judd Devermont, the director of the Africa programme for the Center for Strategic and International Studies, a US think-tank.

“The domestic and security tumult in Chad may draw some troops away from the missions in Mali and the Liptako-Gourma tri-border region, depriving France of its most effective partner,” he added.

“It will have less impact on the Lake Chad Basin where Chadian troops already have pulled troops from far-flung forward operating bases in Nigeria to reconcentrate its defences on the border.”

Wasting no time, the military installed Deby’s 37-year-old son Mahamat Idriss Deby, a four-star general who previously commanded the elite guard under the presidency and was also a deputy commander of the Chadian forces in Mali, as Chad’s interim president. This despite the fact that, constitutionally, the leader of the national assembly should have assumed the role.

Mahamat Deby, also known as Mahamat “Kaka”, will now lead the country for the next 18 months as the head of a transitional military council.

FACT members rejected Mahamat Deby’s swift appointment, saying “Chad is no monarchy”, and threatened to continue their advance towards N’Djamena.

Some political opposition parties have called the formation of the military council an “institutional coup”, while others said the dynastic overtones of the succession could be enough to stoke stronger calls for a change in leadership and set in motion a period of instability and violence – with domestic and regional ramifications.

“It’s important for [our] security efforts to take into account the passing of the Chadian president, not just for Chad itself, but also for the other countries of the G5 Sahel and countries like the Central African Republic (CAR) and Nigeria,” said Ousseni Tamboura, communications minister of Burkina Faso.

“It’s urgent we consider the security and the political future of Chad to help it overcome this difficult test,” he added.

Alex Thurston, assistant professor of political science at the University of Cincinnati, with a focus on the Sahel conflict, said the meaning of Deby’s death “depends on what happens now in Chad”.

“If the next ruler replicates Deby’s model, maybe the status quo can continue in Chad and with Chadian deployments,” he said.

“The status quo is, in many ways, very bad for Chadians. Deby’s power was already brittle, and if his successor loses control, fragmentation in Chad will have ramifications for Niger, CAR, Darfur and beyond,” Thurston added.

According to Freedom House, a United States-based NGO that carries out research on democracy, Chad scores 3/40 for political rights and 14/60 for civil liberties.

Despite accusations of a democratic deficit and a litany of human rights abuses by its military, Chad has been a key ally in the West’s military strategy in the region on two fronts: against al-Qaeda and ISIL (ISIS) in the western portion of the Sahel, and against Boko Haram in the Chad Basin.

What has made Chad attractive to Western countries is its geography, military force and friendly leadership.

It is of particular interest to France, the former colonial power in the region, where it still maintains numerous business interests. France’s military effort in the Sahel region, the 5,100-strong Operation Barkhane, is headquartered in N’Djamena.

As such, the front pages of French newspapers Le Monde, Liberation and Le Figaro all ran with the story of Deby’s death on Wednesday morning.

On Tuesday, the French ministry for Europe and foreign affairs released a statement which said, “Chad is losing a friend of France and a reliable partner who has worked tirelessly for the security of his country and the stability of the Sahel.”

On Thursday, French Foreign Minister Jean-Yves Le Drian justified the military takeover in the wake of Deby’s death, underlining the importance of stability at this stage.

“There are exceptional circumstances,” said Le Drian, who is expected to accompany French President Emmanuel Macron to Chad on Friday for Deby’s funeral and talks with the new military rulers.

For his part, Ned Price, spokesman for the United States Department of State, told reporters that the US “would be concerned with anything that stands in the way” of a transition to civilian rule.

But whatever happens within Chad in the months ahead is sure to be felt far beyond its borders.

Lassane Sawadogo, executive secretary for the ruling People’s Movement for Progress (MPP) party in Burkina Faso, said Chad’s allies need to take this into account, given its significance in the fight in the Sahel, and act quickly.

“The countries of the subregion must get together very quickly to assess the situation in light of the new circumstances,” he said. “It is urgent to find solutions to fill the void and manage threats and risks.”