U.S. Secretary of State John F. Kerry and Kenyan President Uhuru Kenyatta in Nairobi after a bilateral meeting on Aug. 22. (Ho/AFP/Getty Images)

Secretary of State John F. Kerry on Monday condemned a recent outburst of violence in South Sudan as “tragic and in some cases even reprehensible,” and said the United States would not automatically continue to provide humanitarian support for the country unless its leaders commit to peace.

Kerry also defended a recent decision by the United Nations Security Council to send 4,000 peacekeepers to South Sudan, in addition to the 13,000 already there. The peacekeepers have been accused of doing little to protect South Sudanese civilians and foreign aid workers who were raped and murdered by combatants during clashes last month.

The United States played a key role in the creation of South Sudan, which became independent from Sudan in 2011. The country collapsed into civil war in 2013, leaving tens of thousands dead in fighting that occurred largely between ethnic groups aligned with the country’s two most prominent politicians. In 2015, the United States helped broker a peace deal between those politicians, President Salva Kiir and First Vice President Riek Machar.

But in July, that deal fell apart as violence consumed the capital, Juba. Machar fled, announcing last week that he had arrived in Congo. Kerry called for the resumption of the country’s peace process, but it is unclear when, or if, Machar will return.

Kerry spoke at a news conference after meeting with Kenyan President Uhuru Kenyatta and foreign ministers from around the region. Kerry is on a trip that also includes stops in Nigeria and Saudi Arabia.

He announced $138 million in new humanitarian assistance to South Sudan, aimed at getting food, water and medicine to a population that has become ever more desperate as recent fighting has prompted thousands to flee their homes. The U.S. government has already provided the country with about $1.6 billion in aid since late 2013, according to the U.S. Agency for International Development.

But Kerry said he had made clear to South Sudan’s leaders that the money would not continue indefinitely.

“We made it crystal clear that this is not forever. We’re not just going to fill in a void. We are not just going to provide help incessantly if they are not going to provide security and do the things necessary to deliver to their people,” he said. He called on the country’s leaders to care for their citizens and “refrain from violent and provocative acts.”

Government forces, which are under Kiir, struck U.N. compounds and personnel during last month’s fighting, raided warehouses full of emergency food rations and blocked U.N. convoys from providing humanitarian support.

Experts have questioned the effect that the additional U.N. troops would have — both because of the peacekeepers’ dismal record of protecting civilians and the South Sudanese government’s lack of respect for the U.N. mission. Defending civilians is part of the peacekeepers’ mandate.

Kerry said that the peacekeepers were not being sent as “a response to the overall crisis,” but would be able to guarantee freedom of movement for civilians and humanitarian workers in Juba.