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The resurgent conflict in the vast African nation of Congo involves several armed groups, at least two other countries and the minerals that go into handhelds and laptops, probably including the one you're reading this story on if you're seeing it on a device.

It's complicated but it boils down to a struggle for wealth, ethnic animosity and a lack of central government control. Here are some of the issues:

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THE COUNTRY

Congo is sub-Saharan Africa's biggest country, stretching from the Atlantic Ocean in the west to two-thirds of the way across the continent. It is plagued by a lack of roads and railways. The feeble government in the capital Kinshasa is nearly 1,000 miles (1,600 kilometers) away from Goma, the strategic eastern town that was seized by M23 rebels on Nov. 20. A succession of rebel groups and warlords have for years taken advantage of the power vacuum to get a piece of the mining action in eastern Congo.

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MINERALS

Eastern Congo is estimated to have mineral deposits worth trillions of dollars, according to mining experts. The area holds about 70 percent of the world's supply of tantalum, a metal used in cellphones, tablets, laptops and other computers, according to the U.S. Geological Survey. The eastern region also has massive amounts of gold, tin, tungsten, copper, coltan and cobalt. Much of the ore mined is smuggled out of Congo and passes through Rwanda, Uganda or Burundi, according to the Enough Project, a Washington-based organization campaigning against conflict minerals. Some 450,000 artisanal miners work in eastern Congo, according to the U.S. Geological Survey.

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M23 REBELS

The M23 rebel group was formed almost eight months ago by former members of a now defunct insurgent group that had been incorporated into the Congolese army as part of a March 23, 2009, peace agreement. The new group was created by the former rebels who deserted from the army. Their name refers to the date of the peace agreement, which M23 accuses the government of not honoring. Since May, M23 has seized territory in North Kivu province, culminating last week with the capture of Goma, a lakeside city of 1 million and a key trading hub bordering Rwanda.

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THE TERMINATOR

M23 is believed to have been created by warlord Bosco "The Terminator" Ntaganda, who had been a leader of the former rebel group, the National Congress for the Defense of the People, or CNDP. The CNDP was backed by Rwanda, which also allegedly arms and gives other support to M23. As part of the 2009 agreement, Ntaganda, Ntaganda was made was made a general in the army and deputy commander for an operation meant to go after a militia made of Hutus who took part in Rwanda's genocide. In early 2012, Congolese President Joseph Kabila came under international pressure to arrest Ntaganda and transfer him to the Hague to face war crimes charges in the International Criminal Court. Ntaganda, avoided immediate arrest, launched a mutiny and was joined by some loyal men who are believed to have formed M23. Kabila, whose father had led a rebellion in 1997 that toppled dictator Mobutu Sese Seko, had also vowed to dismantle a parallel chain of command that Ntaganda established in eastern Congo's North Kivu and South Kivu provinces. Ntaganda had operated lucrative businesses with other army officers in the east, including a smuggling racket taking minerals into neighboring Rwanda, according to a U.N. report released on Nov. 21.

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RWANDA

Rwanda has backed rebels groups in eastern Congo as a defense against other militias of Hutu extremists, many responsible for Rwanda's 1994 genocide, who operate in east Congo. But many analysts also think Rwanda is motivated to support sympathetic power networks in the east so that it can profit from the export of smuggled Congolese minerals. M23's success has been due to direct support from powerful figures in Rwanda and neighboring Uganda, according to U.N. investigators researching the conflict in eastern Congo. The report says that high-ranking Rwandan government and army figures, most notably Defense Minister James Kabarebe and Chief of Defense Staff Charles Kayonga, have supported the M23 by providing recruits, sophisticated arms, ammunition and finances. Rwanda also wants to use M23 as a Tutsi force to counter the Hutu rebels of the FDLR, also operating in eastern Congo, said the U.N. report. The Rwandan government of President Paul Kagame vehemently denies it supports M23.

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UGANDA

Uganda has also supported the M23, although on a smaller scale, said the U.N. report. This has allegedly been driven by a few powerful Ugandans intent on profiteering from access to Congo's rich mineral resources. Uganda denies supporting M23. The rebels feel comfortable in Uganda and can come and go as they wish. Their external relations official is now based in Kampala, Uganda's capital. The U.N. report did not accuse Uganda of orchestrating an official policy of backing the rebels, but it said some within the military were using their influence to procure arms and ammunition for the rebels. The U.N. investigators even claim that units of the Rwandan and Ugandan armies have fought alongside M23 soldiers against the Congolese army. A "mixed brigade" of Rwandan and Ugandan soldiers allegedly numbered more men than the massed ranks of the M23 forces, said the U.N. report.

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WHAT'S NEXT

The Congolese army — underfed, poorly supplied and rarely paid — have repeatedly retreated in the face of M23 attacks. Even if the rebels withdraw from Goma now, military experts say the well-organized, well-supplied M23 will remain to seize the key city again. U.N. investigators claim that the ultimate goal of M23 and Rwanda is the annexation of the North and South Kivu provinces and the region's mineral wealth. They say the battle for Goma may be just the beginning of a long and bloody conflict for control of eastern Congo.