A Sudanese man carries a bed past South Sudan People's Liberation Army (SPLA) national army soldiers patroling the town of Bentiu following its capture, Jan. 12, 2014.
A Sudanese man carries a bed past South Sudan People's Liberation Army (SPLA) national army soldiers patroling the town of Bentiu following its capture, Jan. 12, 2014.

The United States and the East African bloc mediating peace talks for South Sudan, IGAD, on Thursday condemned a new outbreak of fighting in Unity state and warned that new sanctions could be imposed on South Sudanese leaders who obstruct peace.

"We call on both sides – both of whom have committed violations of the agreement that have delayed peace –  to ensure their forces refrain from further actions that violate the January 23 Cessation of Hostilities Agreement and undermine the peace process in South Sudan," U.S. State Department spokeswoman Jen Psaki said in a statement.

Psaki called the conflict in South Sudan "senseless" and "man-made."

She said that although President Salva Kiir and his former deputy, Riek Machar, who are on opposing sides in the conflict, recently took responsibility for the crisis in the world's newest nation, the latest attacks on Bentiu "demonstrate that the SPLM/A-in-Opposition (led by Machar) has yet to abandon violence to achieve its goals."

The United States could impose further sanctions on anyone who continues to obstruct peace in South Sudan, commits human rights violations or blocks humanitarian assistance, Psaki said in a statement.

IGAD blames rebels

The Intergovernmental Authority on Development (IGAD) also blamed Machar's opposition movement for the latest fighting.

"The ongoing fighting in and around Bentiu... demonstrates that the SPLM/A In Opposition has yet to abandon the option of war," IGAD said in a statement.

"The already dire humanitarian situation throughout South Sudan is further imperiled by this violence," the statement said.

Nearly 1.9 million people have fled their homes and hundreds of thousands face hunger in South Sudan. The U.N. Office for the Coordination of Humanitarian Affairs (OCHA) says around 235,000 children in the country could suffer from severe acute malnutrition by the end of the year.

UN 'waving sanctions stick'

Seyoum Mesfin, IGAD's lead mediator at the South Sudan peace talks, warned the warring sides that the international community will take stern action unless the conflict ends.

"The U.N. Security Council is waving the stick of sanctions unless they stop this war. IGAD has said that repeatedly. The African Union is saying it... the European Union is saying it," Seyoum told reporters in Addis Ababa.

The United States and the European Union have already imposed sanctions on military leaders from both sides of the conflict in South Sudan, and U.S Ambassador to the United Nations, Samantha Power, said last month that the Security Council is mulling sanctions.

One of the leaders in South Sudan who is under sanctions is Peter Gadet, the leader of a rebel militia that is active in and around Bentiu.

Gadet, who has been sanctioned by both the United States and the EU, is accused of leading an attack on Bentiu in April, in which more than 200 civilians were killed, including some who were sheltering in mosques, churches and hospitals.

The U.N. Mission in South Sudan (UNMISS) has also accused Gadet of being involved in the shooting down of a U.N. helicopter in August. Four Russian crewmembers died when the helicopter crashed near Bentiu.