The renewed fighting in South Sudan presents a dilemma for the United Nations and the US government, who appear undecided on whether to impose sanctions on the protagonists.

The UN Security Council on Thursday called for an investigation into the ethnic massacres in the country, and warned of sanctions against President Salva Kiir, his rival Dr Riek Machar and other leaders in the country if the violence continues.

“The members of the Security Council strongly reiterated their demand for an immediate end to all human-rights violations and abuses and violations of international humanitarian law, and expressed their readiness to consider appropriate measures against those responsible,” the UNSC said in a statement released after a meeting on South Sudan in New York.

While there appears to be little opposition within the Council to punishing leaders on both sides of the conflict, the 15 members have not reached a consensus on what sanctions would be effective.

They may prove similar to the assets freeze and travel bans that the US recently threatened to impose unilaterally, but neither the Obama administration nor the UN seems firmly resolved on a particular course of action.

On April 3, US President Barack Obama signed an executive order paving the way for targeted sanctions against South Sudan officials responsible for human-rights abuses.

Security experts said on Friday it is possible the UNSC will impose an arms embargo on both the government and rebel forces.

Jonah Leff, the director of operations for Geneva-based NGO Conflict Armament Research, said an arms embargo would be “extremely difficult” to monitor or enforce.

“Arms move quite freely across South Sudan’s borders, and there are several airports and landing strips throughout the country that are unmonitored,” Mr Leff said.

He added that there had been reports that the SPLA had recently procured a large consignment of rifles, but it was not clear who supplied them.

“As for Machar, there have been repeated allegations that Sudan and Eritrea are supplying his forces, but we have not seen any evidence to confirm these claims,” Mr Leff added.

According to US analysts, it appears likely that the White House will trigger its threatened sanctions against the government and rebels within the next week, although action may be withheld until John Kerry, the Secretary of State, makes his visit to South Sudan early in the week.

The analysts said the US had some ability to hurt South Sudanese leaders, some of whom hold US citizenship and many of whom have wealth stowed away in foreign banks that could be affected by a US freeze.

Another possibility suggested by some diplomats is for the Security Council to authorise an investigation by the International Criminal Court into human-rights violations in South Sudan. But such a scenario seems unlikely, due in part to lingering political concerns about the ICC’s exclusive focus on Africa.

Some analysts suggest that the US has a special responsibility to do more than threaten to impose sanctions, given the instrumental role it played in brokering Independence for South Sudan.

US ambassador to the UN Samantha Power condemned the “outrageous” deliberate targeting of civilians and urged the two sides to end the violence, but her statement suggests that Washington prefers any sanctions to be imposed by the UN with the support of the Security Council where China, which has interests in the country’s oil sector, sits.

Chinese diplomats at the Security Council said they would “conscientiously participate” in the discussions on South Sudan, but refused to say whether they would support sanctions.

French ambassador to the UN Gerard Araud said it may no longer be possible for the UN to co-operate with the South Sudan government, given its involvement in atrocities.

Mr Araud admitted to uncertainty over how the UN could most effectively help put an end to the violence that is destroying South Sudanese society and giving rise to humanitarian disasters, including the spectre of famine.

“I do think we have to have some soul-searching about what the UN should do,” the French diplomat said following the April 23 Security Council meeting. The UN has also accused the Juba-based government of interfering with peacekeeping and humanitarian operations.

Ms Powers specifically urged the Security Council on April 23 to “swiftly create a sanctions regime targeting spoilers of the peace process and those responsible for atrocities.”

The warning follows an upsurge in violence in South Sudan in which thousands have been killed and about a million people forced from their homes, including tens of thousands who fled to UN bases across the country.

The UN’s military mission in South Sudan (UNMISS) is sheltering nearly 80,000 South Sudanese civilians at eight bases around the country. UN officials insist UNMISS is performing heroically, but critics say the mission is failing to fully implement its mandate.

The Blue Helmets were unable to prevent the carnage in Bentiu or an April 17 attack on a UN compound in Bor.

Nuer-led rebel forces are believed to responsible for killing more than 200 Dinka and others in Bentiu, while Dinka-commanded government troops are blamed for the deaths of about 50 Nuer at the base in Bor.

Strapped for funding for peacekeeping operations, the UN is continuing to scramble four months later to transfer troops to South Sudan from other missions in Africa.

UNMISS currently consists of about 10,000 soldiers and police who have been volunteered for service by various UN member-states. The deployment remains well short of the 12,500 personnel authorised by the Security Council at the end of 2013.

A political contest between President Kiir and former vice president Machar within the ruling SPLM party sparked off fighting between troops loyal to either man, before morphing into intra-ethnic violence as the former’s Dinka people and the latter’s Nuer attacked one another.

A ceasefire agreement signed on January 23 in Addis Ababa under the aegis of the Inter-Governmental Authority on Development (Igad) has failed to hold in the absence of a clear enforcement mechanism.

The International Crisis Group said the UN is the only body that can save the country from becoming a totally failed state. But the UNSC must first change the mandate of UNMISS to ensure it is consistent across the country and emphasises protection of civilians.

“Years of failure — across the UN system and from member states — to demand accountability for attacks on peacekeepers and the acceptance of government conditions on civilian and troop movements have left UNMISS ill-equipped and lacking the esprit de corps necessary to provide robust and impartial protection in and around bases where civilians have sought protection,” says the ICG in its latest report on South Sudan.

The report recommends that the UNSC ensure that UNMISS has the capacity to support the Igad mediation in terms of logistics, as well as help the African Union commission of inquiry team.

“The UNMISS mandate and capacity to prevent killings have been fluctuating depending on the given situation. But now that the conflict has turned into basic revenge killings, the peacekeepers must be seen to have the monopoly of violence,” said Jervasio Okot, a political analyst.

For the killing of civilians to stop, ICG said, armed groups must be forced to comply with international humanitarian law by halting targeting of civilians, including stopping combat operations in areas where civilians cannot be distinguished from combatants and avoiding combat in areas around UN bases.

The UNSC asked the UN High Commissioner on Human Rights on April 24 to undertake an investigation of the April 14-16 massacre in Bentiu of hundreds of South Sudanese civilians, mainly Dinka.

Ivan Simonovic, the UN’s Assistant Secretary General for Human Rights, is scheduled to issue a report by the end of April on human-rights violations committed during the four months of civil conflict that erupted in mid-December.

“The UNSC needs to act decisively to impress on the warring parties targeting civilians in South Sudan that they will pay the price for their crimes.

The Bor and Bentiu attacks should be a wake-up call [that] commanders and leaders responsible for abuses on both sides have been let off the hook for too long. Unless they are held accountable for their crimes, the ethnic violence will continue to engulf this young country, with UN peacekeepers left to pick up the pieces,” said Human Rights Watch director for Africa Daniel Bekele.

UN Secretary-General Ban Ki-moon on April 24 telephoned the heads of state of some members of Igad to urge a renewed push for meaningful talks between the warring sides in South Sudan. Igad-sponsored negotiations have produced no progress toward halting the violence, but as Mr Ladsous commented last week, these talks remain “the only game in town.”

Kenya’s President Uhuru Kenyatta on Friday castigated the SPLM in Government and its rival SPLM in Opposition for dishonouring the Cessation of Hostilities at summits of the Igad, in Nairobi in December 2013, and in the Ethiopian capital of Addis Ababa in January and March.

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“We especially reject the possibility that we are creeping into genocide again in our region. We shall not stand by and allow it to happen. The signatories to the Cessation of Hostilities Agreement then went right ahead to ignore the agreements they had entered into and have continued to fight, kill and destroy property with disastrous ramifications. It is heart wrenching for us in Igad, the EAC, African Union and indeed the wider global community to sit and watch atrocities being committed on a daily basis. This must be put to a stop,” said President Kenyatta in a statement.

“We strongly call upon all the parties to bring their military activities and killing of innocent people to an immediate end and bring to account those involved. Failure to do so is unacceptable and will call for concerted effort by the international community to do so. It is up to the region and the global community to ensure that we live up to the promise we made in Kigali, Rwanda, earlier this month: Never again. We in Kenya and the region take that pledge seriously. We are convening an emergency summit of Igad in coming days to deliberate and consider our options,” he added.

As a further indication of the lawlessness rife in South Sudan, a UN convoy of ships carrying food and fuel supplies came under attack on April 24 by unknown parties.

Four barges were travelling on the Nile to the UN base in Malakal when they were targeted by small-arms fire and rocket-propelled grenades, UNMISS reported. Four peacekeepers and crew members were wounded in the attack.

Ndung’u Wainaina, executive director of the International Centre for Policy and Conflict, argues that neither President Kiir nor Dr Machar will stop the violence unless there is substantive incentive for them to do so.

“Right now, they see no threat and/or such incentive. The duty to prevent and halt genocide and mass atrocities lies first and foremost with the state, but the international community has a role that cannot be blocked by the invocation of sovereignty,” said Mr Wainaina.

The ICG report says that it is time to consider a hybrid tribunal with South Sudanese and international judges, similar to the Special Court for Sierra Leone.

But regional forces should only be deployed if they have a clear mandate that supports a political resolution of the conflict; if there are adequate troops and financial resources available for deployment; and if precautions are put in place to ensure they work towards a shared political vision and not troop contributors’ individual interests.

By Kevin Kelley, Daniel Kalinaki and Fred Oluoch.