What you need to know:
- The self-proclaimed lieutenant-general leads a militia called the Patriotic Alliance for a Free and Independent Congo (APCLS), mostly made up of fighters from the Hunde ethnic group, in a coalition dedicated to thwarting the M23's advance.
- The Tutsi-led M23 is one of scores of armed groups active in the DRC's volatile east, many of them legacies of two brutal wars in the late 20th century.
Casting his gaze far and wide from a hilltop in eastern Democratic Republic of Congo, warlord Janvier Karairi commands his forces in the battle against the feared M23 rebel group.
The self-proclaimed lieutenant-general leads a militia called the Patriotic Alliance for a Free and Independent Congo (APCLS), mostly made up of fighters from the Hunde ethnic group, in a coalition dedicated to thwarting the M23's advance.
The APCLS and other armed groups joined forces "to fight the aggressor", Karairi, 60, told AFP reporters in his operational headquarters, a thatched hut in the Kitshanga region of North Kivu province.
Sporting a commando uniform, Karairi has spent more than a quarter of a century in the bush, including a spell fighting the M23 in 2012.
The Tutsi-led M23 is one of scores of armed groups active in the DRC's volatile east, many of them legacies of two brutal wars in the late 20th century.
It briefly occupied provincial capital Goma that year before being beaten back in 2013.
It resumed fighting in late 2021, blaming the Congolese government for failing to honour a commitment to integrate its fighters into the army.
In recent months, the M23 has conquered part of Rutshuru territory near the borders with Uganda and Rwanda.
Kinshasa accuses neighbouring Rwanda of backing the rebels, who now lie around 20 kilometres (12 miles) north of Goma and have made gains further west towards Masisi territory, Karairi's stronghold.
That prompted the battle-hardened militia leader to take up arms against his old foes once again, with his movement controlling much of the area.
'Fighting for my country'
"We continue to protect the population," Karairi said at his headquarters in between phone calls to his troops on the ground. A silence descends every time he speaks.
Accompanying the veteran warrior was Heritier Ndagendange, who had just arrived from Goma with a heavy red bag that another militiaman carried on his head to present to the commander.
Ndagendange said it held ammunition he had brought from Goma after passing several checkpoints manned by the security forces on the road.
"We are rebels, we are good at finding weapons. The government doesn't help us with anything in any case," Karairi said.
He said his hundreds of combatants are unpaid volunteers motivated by the same desire to fight. "Our country will pay us when we finish the job," he claimed.
Baseme, a 25-year-old under his command, proudly declared that he was "fighting for my country." His comrade Mwisha, 23, said he joined the movement "to stand in the way of the aggressors, Rwanda."
An APCLS spokesman said the army's withdrawal from certain key routes had allowed the M23 to make rapid gains.
Ndagendange said Congolese army officers had "betrayed" the cause, and this had forced the APCLS to intervene to stop the M23.
Human Rights Watch (HRW) published a report in October which claimed the Congolese army was collaborating with armed groups -- some of which stand accused of rights abuses -- in the campaign against the M23.
Among them are the Democratic Forces for the Liberation of Rwanda (FDLR), a mainly Hutu group that includes some actors involved in the 1994 Rwanda genocide against the Tutsis.
HRW also said the leaders of several Congolese armed groups, including Karairi's APCLS, met in May to forge a "patriotic" coalition.
The army and the APCLS say they do not fight alongside these militias.
But with a myriad of armed men patrolling the streets of Kitshanga, some in military uniform and others in civilian clothing, a young telephone seller who gave her name as Muhoza said she could no longer tell the difference between them.
"Here you don't know who's who. We're living in total fear, with all these armed groups," she whispered.
Two young Hunde villagers, returning from the fields, said they felt safe since the arrival of the APCLS in their settlement.
On the other hand, a Tutsi woman in Goma said she had to flee Kitshanga when "General Janvier" and his young fighters entered the town.