DAKAR, Senegal (AP) – Rwanda-backed rebels have claimed control of eastern Congo’s strategic city of Goma, the hub of a region containing trillions of dollars in mineral wealth that remains largely untapped.

It marks a sharp escalation in one of Africa’s longest wars, threatening to dramatically worsen a dire humanitarian crisis.

On Tuesday, UN officials reported bodies lying in the streets, widespread looting and outages of electricity, water and internet access. More than 2 million of Goma’s civilian residents, including one million already displaced by the violence, were at risk of “catastrophic” humanitarian consequences, aid groups said.

Analysts said the M23 fighters aimed to control the city of about 2 million people and perhaps other areas in the region nearly 1,000 miles from the Congolese capital.

The rebels’ offensive has sent hundreds of thousands fleeing their homes, in addition to 1 million displaced who are already in Goma, and stretched hospitals to the limit, with hundreds of wounded coming in every day as civilians get caught in the crossfire.

Here is what to know about the conflict.

Who Are the Rebels and What Do They Want?

The M23 group is one of about 100 armed factions vying for a foothold in eastern Congo, where a decades-long conflict has raged. The group, made up primarily of ethnic Tutsis who failed to integrate into the Congolese army, led a failed insurgency against the Congolese government in 2012. It was then dormant for a decade, until its resurgence in 2022.

Between 1996 and 2003, the region was at the heart of a protracted conflict dubbed “Africa’s world war,” as armed groups fought over access to metals and rare earth minerals such as copper, cobalt, lithium and gold. Up to 6 million people died.

The conflict can be traced to the aftermath of the 1994 genocide in neighboring Rwanda, where Hutu militias killed between 500,000 and 1 million ethnic Tutsi, as well as moderate Hutus and Twa, Indigenous people.

When Tutsi-led forces fought back, nearly 2 million Hutus crossed into Congo, fearing reprisals. Tensions between Hutus and Tutsis have repeatedly flared in Congo since then.

Rwandan authorities have accused the Hutus who fled of participating in the genocide and alleged that elements of the Congolese army protected them. They have argued that the militias formed by a small fraction of the Hutus are a threat to Rwanda’s Tutsi population.

M23 claims to defend Tutsi and Congolese of Rwandan origin from discrimination. Critics say it is a pretext for Rwanda to obtain economic and political influence over eastern Congo.

Why Is Control of Eastern Congo So Important?

As the world relies more than ever on Congo’s metals and rare earth minerals to produce electronics, the stakes have risen. Neighboring Rwanda and Uganda have financial interests in Congolese mines, as well as China and the United States.

Most of Congo’s mineral resources, estimated to be worth $24 trillion, remain untapped, according to the U.S. Department of Commerce last year, which called the country the world’s leading producer of cobalt, key to making batteries.

Little of the region’s wealth has trickled down to Congolese citizens, with 60 percent out of its 100 million residents living below the poverty line. Instead, fighting over natural resources has destabilized the country.

What Is the Role of Neighboring Rwanda?

Congo, the United States and UN experts accuse Rwanda of backing the M23, which had hundreds of members in 2021. Now, according to the United Nations, the group has around 6,500 fighters.

While Rwanda denies that claim, it acknowledged last year that it has troops and missile systems in eastern Congo, allegedly to safeguard its security. UN experts estimate there are up to 4,000 Rwandan forces in Congo.

Analysts say that Rwandan troops in eastern Congo have been increasingly active in recent weeks.

Why Is Goma Important for the Rebels?

The city is a regional hub for trade, security and humanitarian efforts, and its airport is key for transporting supplies.

Since 2021, Congo’s government and allied forces, including Burundian troops and UN troops, have been keeping the rebels away from Goma.

The capture of such a large city will be a huge boost for the rebels and a major defeat for government forces.

Goma’s fall would also have a “catastrophic impact on hundreds of thousands of civilians, putting them at risk of heightened exposure to human rights violations and abuses,” said Ravina Shamdasani of the UN human rights office.

Is This Likely to Resolve Like the Last Time?

In 2012, the rebels seized Goma and controlled it for about a week but surrendered the city after mounting international pressure on Rwanda—including suspension of aid from the United States and Britain.

But analysts say this time around, it will be more difficult.

“Previously, they [M23] had clear demands to be integrated into the DRC army and have greater participation in the political process,” said Darren Davids, an analyst with the Economist Intelligence Unit. But now, he said, “it seems like M23, with the help of Rwanda, are intent on holding control of Goma and, more specifically, the supply chain routes in North Kivu.”

The rebels could use Goma as a bargaining chip, strengthening their position in possible negotiations with Congo.

What Is the Situation for Civilians?

There are 4 million displaced people in eastern Congo, and the rebels’ escalated offensive sent additional hundreds of thousands fleeing their homes and displacement camps in recent weeks.

About 300,000 people sheltering in camps on Goma’s outskirts fled into the city as front lines moved over the weekend, only to find themselves trapped by the violence once again as rebels entered the city, according to the UN.

The airport closed, roads were blocked, and aid groups said they were unable to provide lifesaving support to those in need. Medical facilities are at double their capacity. The main hospital in Goma treating the wounded, run by the International Committee of the Red Cross, is stretched beyond its limits, with tents set up in its courtyard to accommodate civilians wounded by bullets and heavy artillery.

Some civilians, desperate to flee the fighting, crossed into Rwanda to seek safety. More than 1,000 Congolese have been registered since Monday, according to Rwandan authorities.