The Democratic Republic of Congo is slowly recovering from a conflict known as Africa's first world war, which led to the loss of some five million lives between 1994 and 2003, but many eastern areas are still plagued by violence as various rebel groups continue to operate there.
What has the fighting been about?
DR Congo is extremely wealthy - and extremely big. Similar in size to Western Europe, it is rich in diamonds, gold, copper, cobalt and zinc.
The country also has supplies of coltan, which is used in mobile phones and other electronic gadgets, and cassiterite, used in food packaging.
Unfortunately for the people of DR Congo, its resource wealth has rarely been harnessed for their benefit.
This vast country has hardly any roads or railways, while the health and education systems lie in ruins.
Instead the natural riches have attracted rapacious adventurers, unscrupulous corporations, vicious warlords and corrupt governments, and divided the population between competing ethnic groups.
In the early 20th Century, Belgian forces arrived and enslaved millions, while King Leopold ruled the country as his personal fiefdom.
During a painful independence struggle in the 1960s, the vast country almost disintegrated as regions fought each other.
But Joseph Mobutu seized power in 1965 and set about crushing internal rebellions and unifying the nation - eventually changing its name to Zaire.
However, Mobutu was soon seduced by wealth and once he controlled most of the country and achieved a level of stability and prosperity, he began using the country's riches for one thing - to ensure he remained in power.
As his rule went on, his plunder continued and the country gradually slipped out of his control.
The 1994 genocide in neighbouring Rwanda hastened his downfall and helped plunge DR Congo into the deadliest conflict in African history.
Why did Rwanda's genocide affect DR Congo so badly?
Eastern DR Congo has porous borders.
After Rwanda's genocidal Hutu regime was overthrown, more than two million Hutus are thought to have fled into DR Congo fearing reprisals against them by the new, Tutsi-dominated government.
Among them were many of the militiamen responsible for the genocide.
They quickly allied themselves with Mobutu's government and began to attack DR Congo's sizeable population of ethnic Tutsis, who had lived in the country for generations.
Rwanda's Tutsi government started to back rival militias, fighting both the Hutu militias and Congolese government troops.
The Tutsi militias, allied to other local groups backed by Uganda, eventually marched on Kinshasa and overthrew Mobutu's government.
They installed Laurent Kabila as president and he once again renamed the country - from Zaire to DR Congo.
But Mr Kabila failed to expel the Hutu militia and tiny Rwanda, which had put him in power, soon sent a new force to oust him.
Mr Kabila then called in help from Zimbabwe, Namibia and Angola, and for the next five years all six countries, and others, fought a proxy war on Congolese land.
All sides were accused of using the cover of the war to loot the country's riches.
More than five million people died in the war and its aftermath - mostly from starvation or disease.
Although the war was declared over in 2003, the east of the country continues to be unstable.
Has DR Congo achieved any kind of peace?
Most of the country has now found peace and the central government has slowly reasserted control.
The country even started to live up to its name by having the first democratic elections in more than four decades, which saw the late Laurent Kabila's son, Joseph, elected as president.
But a proxy war between Rwanda and the Kinshasa government continued in the east until the end of 2008.
Notorious Tutsi warlord Gen Laurent Nkunda - who most analysts believe was backed by Rwanda - waged a campaign to destroy Hutu rebels from the Democratic Forces for the Liberation of Rwanda (FDLR).
He accused the government of backing the FDLR.
A sea-change in the conflict came about in late 2008 when Rwanda and DR Congo joined forces to combat the FDLR in the provinces of North and South Kivu.
As part of the deal, Gen Nkunda was taken out of the country and put under house arrest in Rwanda - where he remains.
But the bitter conflict has continued unabated and Congolese government troops, backed by thousands of UN peacekeepers, have failed to defeat the FDLR rebels.
Reports of mass rapes, killings and other atrocities committed by rebels and government troops continue.
The deal between DR Congo and Rwanda has also collapsed, with a new rebel group, the M23, largely made up of former Nkunda loyalists, becoming increasingly active in eastern DR Congo in 2012.
The DR Congo government has repeatedly accused Rwanda of backing the M23. The group was initially said to have been led by Bosco "Terminator" Ntaganda, who is wanted by the International Criminal Court (ICC) on war crimes charges.
Its claims have been given credence by a UN panel investigating the conflict.
It says M23 leaders "receive direct military orders" from Rwanda's chief of defence staff, Gen Charles Kayonga, "who in turn acts on instructions from the minister of defence", Gen James Kabarebe.
It also says Kigali has supplied the M23 with heavy weapons and stepped up recruitment for the group - allegations that President Paul Kagame's government has strongly denied.
The UN panel also accuses Rwanda's regional rival, Uganda, of backing the rebels.
Ugandan army commanders "sent troops and weapons to reinforce specific M23 operations and assisted in M23's recruitment and weapons procurement efforts in Uganda", the report says.
Uganda has dismissed the allegations as "hogwash".
What is the UN doing to end the conflict?
The UN's peacekeeping mission has been in DR Congo since 1999.
It is one of the biggest peacekeeping operations in the world, with almost 20,000 personnel on the ground.
It is mandated to protect civilians and also help with the reconstruction of the country.
It has played a key role in organising democratic elections in DR Congo and has launched military operations against various rebel groups.
But a 2009 report by UN-commissioned experts said UN involvement had done nothing to quell the violence - with rebels continuing to kill and plunder natural resources with impunity, and claims that the rebels are supported by an international crime network stretching through Africa to Western Europe and North America.
And the campaign group Human Rights Watch (HRW) has suggested the UN risks becoming complicit in atrocities against civilians.
In August 2010, the UN force was accused of not doing anything to stop the rape of more than 150 women and children within miles of their base near Luvungi, saying they only heard about the attacks 10 days afterwards.
The Congolese government has said it is now capable of maintaining law and order, and wants the UN force to leave the country.
To reflect its changing status, the force changed its name from the UN Organisation Mission in DR Congo - known by its French acronym Monuc - to the UN Organisation Stabilisation Mission - Monusco.