Violence flared again this week in the lucrative and powerful oil-producing states in the east and north, where bitter fighting raged this winter and spring. The new tensions threaten to expand what already seems an intractable conflict.
With peace talks in Ethiopia postponed indefinitely amid new rebel demands over who should participate, rebel and government forces engaged this week near Bentiu, the capital of Unity State, despite two cease-fires.
Meanwhile, a debate in the national capital of Juba over federal vs. state powers in South Sudan reached such a boiling point that the International Crisis Group, a well-known advocacy NGO, called for an emergency UN Security Council session.
Today the UN Security Council threatened sanctions against the South's warring leaders, describing "food insecurity" and warning of a larger famine in the region that includes parts of Sudan as well.
South Sudan broke from Sudan after a 2011 referendum and decades of civil strife. Yet the young nation plunged into its own civil war on Dec. 15 when a power struggle between President Kiir, an ethnic Dinka, and his former vice president, Riek Machar, an ethnic Nuer, cleaved the military in two along ethnic lines.
The fighting has killed more than 10,000 and both sides are charged with committing atrocities that include civilian massacres and rapes. Some 1.5 million people have fled their homes and famine looms because displaced farmers missed the planting season.
The European Union on Friday sanctioned two generals in Unity State, Peter Gadet of the rebels and Santino Deng of the government, for violating a cease-fire. In May, the US sanctioned Mr. Gadet and a different government military leader.
Last week, rebel forces commanded by Mr. Machar moved to cut off supply routes to the government-controlled city of Bentiu; this week the government shelled rebel positions east and south of Bentiu, in the counties of Nhialdiu and Guit, according to UN sources.
The rumble of explosions were heard this week from Bentiu's UN base where tens of thousands of displaced civilians take shelter, prompting aid workers to wonder if it is safe to venture even a few miles to reach civilians.
The rebels apparently repulsed this week's attacks. At least 60 wounded government soldiers were admitted to hospitals in Bentiu, according to sources there. Rebel casualties are unknown since their staging posts are almost impossible to access.
But a spokesman for the government's Sudan People's Liberation Army (SPLA), Philip Aguer, told the Monitor that it was the rebels who were the aggressors on Tuesday. "Since the signing of the cease-fire [the] forces of Riek Machar ... have not stopped attacking SPLA positions," he says.
The Nhialdiu attack occurred during a World Food Programme distribution there to feed some 37,000 civilians. WFP said it had to evacuate its staff due to violence. Sources in Bentiu told the Monitor that government forces has recently accused civilians of bringing food aid to the rebels.
Fears that the crisis could spread beyond Unity and other northeastern states are also percolating strongly in Juba.
Currently, the central government holds the most power. Machar and, more recently, a set of leaders from southern states are calling for more states' rights.
Kiir has sharply resisted the demands. Authorities have warned local media not to report on "federalism," and have confiscated newspapers of those who didn't comply. In the southern region of Equatoria, there are new reports of assassination attempts on pro-federalism politicians, as well as increased troop deployments, and minor clashes.
Kiir also faces difficulties in his traditional heartland of support in greater Bahr el Ghazal. Fighting broke out there last week between Army defectors and government troops. There is also talk of divisions within the ruling party and discontent with Kiir among Bahr el Ghazal elders; the president's office denies these accounts.