Violence in DR Congo's northeastern province of Ituri has claimed nearly 1,000 lives and caused around half a million people to flee their homes, the International Crisis Group (ICG) said on Wednesday.
The flareup has pitched the Hema ethnic group, who are predominantly herders, against the Lendu community, who are mostly sedentary farmers.
The two communities were embroiled in a bloody conflict between 1999-2003 that triggered concern across southern-central Africa and led to the European Union's first foreign military mission, the short-term Operation Artemis.
The latest unrest has worrying ramifications for the notoriously troubled east of the Democratic Republic of Congo, and for neighboring Rwanda and Uganda, which played an important role in the 1999-2003 conflict, the ICG said in a report.
"Since December 2017, violence in the province of Ituri... has left nearly 1,000 people dead and half a million displaced," the ICG said.
So far, Lendu leaders have distanced themselves from the militias, and the Hema have not mounted systematic reprisals, it said.
However, "they (the Hema) do not rule out mobilizing their youth if attacks continue," it said.
"Young Hema have organized into self-defense groups and erected roadblocks in Ituri, which should be seen as forewarning of the risk of ethnic confrontation."
The report called on President Felix Tshisekedi's government to "negotiate the surrender" of Lendu militias, as part of a broader dialogue between the two communities and others.
It also suggested a four-party summit, bringing in the DRC with Angola, Rwanda and Uganda, to "help address the conflict's regional dimensions."
North and South provinces, which lie to the south of Ituri, are in the grip of militia groups that typically claim to defend the interests of given ethnic groups, and fight over resources in the mineral-rich region.