South Sudan spiralled into civil war in 2013, just two years after gaining independence from Sudan.
Haley was the first senior member of President Trump’s administration to visit South Sudan where she met one on one with Kiir.
“I let him know that the United States was at a crossroads and that every decision going forward was going to be based on his actions,” Haley told reporters after the meeting in the capital Juba, the report said.
The United Nations has warned that the violence in South Sudan was providing “fertile ground” for genocide. Kiir’s government has since denied U.N. allegations of ethnic cleansing.
Some 4 million people have been forced to flee their homes to neighbouring countries due to the violence.
Haley had to cut short a visit to a camp for South Sudanese displaced by the violence amid rowdy anti-Kiir protests.
“He understood that Americans were disappointed in his leadership in South Sudan, I made that very clear. And he understood that all the aid or help that he hopes will go forward is not a given,” she said.
According to Haley, Washington was considering how to pressure Kiir into peace, though noted that withdrawing aid may not work.
The Trump administration last month imposed sanctions on two senior South Sudanese officials and the former army chief.
Speaking to South Sudan’s Eye Radio, Haley said that they have lost trust in the government and the only way to regain the trust is through the actions of taking care of the people.
She demanded that Kiir allow full and consistent humanitarian aid access and bring peace and stability to the country. She said she pushed a timeline for Kiir to act, but declined to elaborate, the report said.
Nhial Deng Nihal, a senior adviser to Kiir, said the president told Haley his government and a U.N. peacekeeping mission in South Sudan had established “mechanisms that work jointly to improve and address the humanitarian problems.”