Time to Get Serious With South Sudan

South Sudanese from the city of Malakal took refuge behind the walls of the United Nations compound there.

Since the founding of the nation of South Sudan five years ago, its citizens have gone from a brief moment of exhilaration and promise to the cruel reality of tribal violence, depredation and despair. Their leaders have failed them, and so has the United Nations Security Council, which is once again scrambling for a solution to end rampant killing and other abuses. One move the Council could make immediately is to impose a long-overdue embargo on arms shipments, especially to the government forces that have been largely responsible for the bloodshed.

The present crisis, in which at least 73 civilians have died, began last month when fighting broke out in Juba, the capital, ending the latest in a series of brief cease-fires in a civil war between troops loyal to President Salva Kiir and those backing Riek Machar, the former vice president. The war first erupted in December 2013.

Last week, an investigation by the United Nations high commissioner for human rights, Zeid Ra’ad al-Hussein, placed most of the blame for the violence, which it said included mass rapes, on Mr. Kiir’s forces. Mr. Hussein said that while some civilians were killed in the crossfire, others were summarily executed by government forces who appear to have singled out members of the Nuer, an ethnic group loyal to Mr. Machar. The investigation also found that these same forces committed most of the 217 cases of sexual violence, many involving minors.

The 13,000 United Nations peacekeeping troops and police officers in South Sudan have been ineffectual, unable even to protect civilians in United Nations-run refugee areas, called protection-of-civilian sites. During an attack in February on one of those sites in the northern city of Malakal, peacekeepers made major tactical errors that contributed to a massacre that claimed an estimated 30 lives and was planned or at least supported by government forces. Some of the peacekeepers at Malakal were found to have retreated from their posts or waited for written instructions from headquarters before acting to protect the civilians.

The Malakal episode was only the most recent evidence that the peacekeeping operation, dogged by failures in Rwanda in 1994 and Srebrenica in 1995 during the Bosnian war, is dysfunctional and in need of an overhaul, especially when it comes to protecting civilians. Even on an ordinary day in South Sudan, women who need to leave the camps to get food for their families at the market cannot do so without the risk of being raped.

On Sunday, the United States proposed in a draft resolution that the Security Council authorize an additional 4,000 peacekeepers to secure Juba, the airport and other key facilities. The resolution also calls for an arms embargo, but only if the government does not cooperate with the expanded peacekeeping force. The Security Council has threatened several times in the last 18 months to block arms shipments without making good on the threat.

And the Obama administration, apparently fearful of losing leverage with Mr. Kiir, has refused to cut off the arms flow. While such a ban would affect both sides, experts believe it would have more impact on the government, the only side with heavy weapons, including helicopter gunships from Ukraine.

Severing that supply chain, as well as the trade in tanks and artillery, could actually get Mr. Kiir’s attention.