Several clashes involving thousands of combatants in South Sudan's Jonglei state have highlighted the volatility of the world's newest country, affecting some 140,000 people. A major new offensive has been announced to start in early March.
What is Jonglei?
With a surface area of 123,000 sqkm, the largest and also the most densely populated of the 10 states in South Sudan. It suffers from a dearth of basic infrastructure such as roads, as well as chronic insecurity rooted in resource conflicts, and frequent floods.
Crop production is the primary economic activity, although cattle and fishing play an important role in livelihoods. Sudan's second civil war began in Jonglei in 1983. the region is home to six Nilotic ethnic groups: the Nuer, Dinka, Anyuak, Murle, Kachipo and Jieh.
Its lack of infrastructure has greatly limited the interest of external investors; French oil giant Total has been unable to explore its concessions there. Stability is a prerequisite for fulfilling the tourism potential offered by some of Africa's largest migrations of wildlife.
Who are the combatants?
Broadly, two communities: the Lou and other Nuer groups, fighting under the resurrected banner of the White Army, local defence units initially set up to protect cattle and property, which were militarized during the 1983-2005 civil war; and the Murle, a minority group based mainly in Jonglei's Pibor county.
Some members of the powerful Dinka community have joined the White Army.
What drives the conflict?
Like many proximate livestock-raising communities in marginal lands, rival groups in Jonglei have a long history of raiding each another's cattle, and arming themselves to defend against such raids.
The civil war led to a massive increase of small arms as both Khartoum and the then-rebel Sudan People's Liberation Army (SPLA) mobilized various communities, fomenting localized proxy conflicts. Such support is reported to have continued well after the 2005 signing of the Comprehensive Peace Accord.
Recent years have seen an increasing sophistication in the retaliatory cattle raids, with the use of satellite phones, modern weapons and military tactics.
Deaths resulting from these raids have risen accordingly and clashes have evolved from targeting only armed youths to attacking - or abducting - any members of a rival community, including women, children and the elderly.
In 2011, inter-communal violence claimed 1,100 lives in Jonglei.
Other contributory factors are a scarcity of central government authority, security, development and justice mechanisms, as well as a change in social fabric that has left elders with much less influence over the youth, many of whom are being initiated into combat at a very young age.
The latest large-scale Lou Nuer offensive was preceded by an announcement that their intention was to "invade Murleland and wipe out the entire Murle tribe on the face of the earth". Claiming that the Juba government had failed to protect their cattle, children and women, they said they had to take the matter into their own hands "through the barrel of the gun".
The Murle contend they are discriminated against, sidelined for development projects and under-represented in the political sphere. At state government level, they say representatives are given little power or money to improve things, and that the authorities often describe the Murle as "pests" or a "nuisance".
Underdevelopment is considered a conflict driver. Pibor county is a vast area with just one aid agency providing medical services to more than 160,000 people, a dearth of schools and no employment opportunities.
Mass devastation and some 80,000 heads of cattle taken from Murle areas in January have left tens of thousands homeless and dependent on overstretched aid agencies for food, after crops were scorched in attacks.
What are the effects of the violence?
The top government official in Pibor reported 3,000 deaths, a figure that is impossible to confirm given the large area involved and access difficulties. Survivors have spoken of seeing hundreds of bodies near villages after attacks.
The UN has registered more than 140,000 people in Jonglei needing assistance, many of them displaced.
Cattle have been stolen and people made homeless in their tens of thousands. Large areas under cultivation have been scorched.
Without cows and the women they saved years to raise enough cattle to marry, many men are destitute, with little or no ability to rebuild a modicum of economic security. Such disaffection is likely to fuel the cycle of violence.
Recent attacks have led to the deliberate, widespread destruction of essential basic services, such as water points, health posts and schools, as well as crucial humanitarian centres, where supplies were looted. Such destruction greatly complicates the return of the displaced populations.
In Pibor county, medical charity Médecins Sans Frontières (MSF) has warned of a high number of malaria cases from people sleeping outside, and rising levels of acute malnutrition.
MSF has treated numerous gunshot and stab wounds and expressed shock at the number of women, children and elderly people hurt in attacks, often in the presence of family members, leading to psychological trauma.
Why were civilians not better protected?
The UN Mission in South Sudan (UNMISS) was able to track an 8,000-strong column of armed men marching towards Pibor village before some of the worst violence. But with only 400 peacekeepers and 800 government troops in place, they were vastly outnumbered, and urged residents to flee the column and take refuge behind their defensive lines in Pibor. UNMISS also said the diffuse and unpredictable nature of the attacks on remote villages compromised its ability to protect civilians.
UNMISS has since increased its Jonglei presence to around 1,100 peacekeepers in new permanent bases, roughly half the mission's in-country combat-ready troops, and has called on Juba to deploy a "a significant number" of troops to fill substantial gaps in a planned buffer zone.
The UN force's capacity will be affected by the April departure of its contingent from Russia, which provides many of UNMISS's pilots and aircraft. In late 2011, Russian pilots went on strike over alleged harassment by SPLA forces in Jonglei.
The army said it would bring up to 6,000 soldiers to Jonglei - where, local officials say, 3,000 SPLA troops are currently deployed, 1,000 of them in Pibor town. Locals say the presence of the troops will not necessarily deliver protection, especially if the individual soldiers are drawn from the same community as some of the combatants, which would limit their willingness to engage militarily.
What is being done to prevent more violence?
The government has said the army will forcibly disarm all communities in Jonglei state in the near future. Security experts have deemed this premature and an extremely dangerous move that could spark mass violence unless carried out in conjunction with comprehensive peace talks and by soldiers belonging to none of the ethnic groups involved in the violence.
They say lessons must be learnt from previous operations - notably the 2006 forced disarmament of the White Army in Jonglei, during which several hundred Nuer youths were killed - which tended to expose disarmed communities to attack, leading them to quickly obtain new weapons.
There has been little in the way of dialogue between rival groups, despite repeated appeals by religious leaders, community elders and aid agencies.
Instead, the rhetoric is increasingly combative. The "Nuer and Dinka White Army" recently released a statement saying some 30,000 "well-armed youth" comprising Dinka and Nuer in Jonglei and 10,000 Ethiopian Nuer, would from early March embark on "Operation Savanna Storm" with the aim of preventing future raids by Murle youth.
"The operation will be permanent until Murle do not pose security threats to their neighbours," the statement said.