The United States is providing $180 million in emergency aid to address a food crisis in South Sudan.
White House National Security Adviser Susan Rice said the people of South Sudan face the worst food shortage in the world. She blamed the suffering of the South Sudanese on their leaders' inability to put the people's interests ahead of their own.
The money for the food aid is coming from USAID, as well as a Department of Agriculture trust.
The White House says the U.S. has already provided South Sudan with more than $456 million in humanitarian aid, but more is needed because of the threat of famine.
Also on Tuesday, a delegation from the U.N. Security Council warned that the risk of famine and reports of growing arms imports could bring fresh woe to South Sudan, urging the state's warring leaders to resolve their differences.
At least 10,000 people have been killed since fierce fighting erupted in South Sudan in December, pitting President Salva Kiir's government forces against supporters of Riek Machar, his former deputy and longtime political rival.
Adding to the country's many problems, aid agencies say South Sudan could be headed for the worst famine since the mid-1980s, when malnutrition swept through East Africa and killed over a million people.
"There is a grave risk of famine that now looms, that hangs over this visit," United States ambassador to the United Nations Samantha Powers told reporters, saying 50,000 children under five were at risk of dying of malnutrition in the coming months.
"Moreover, as you all know, the killing is continuing, notwithstanding the fact that a cessation of hostilities has been signed," added Powers, who was part of a group of U.N. Security Council ambassadors visiting the country.
South Sudan's opposing parties failed to meet an Aug. 10 deadline to form a transitional unity government, which was agreed as part of a ceasefire deal signed in January that has been violated by both sides.
Even as discussions continue in the capital of neighboring Ethiopia, Addis Ababa, media has reported that the government has imported a variety of weapons from China.
"We hear very worrying reports of more arms being brought in to this country in order to set the stage for ... another set of battles when the dry season commences," Powers said.
"This is deeply alarming and so the round of talks now underway in Addis have to be taken seriously by both parties and there has to be urgency."
Combat in the nation that won independence from Sudan in 2011, has played out along deep ethnic fault lines, with Kiir's Dinka community battling Machar's Nuer.
More than one million people have been displaced by the violence and more than 400,000 have fled the country. The U.N. peacekeeping operation in South Sudan is sheltering nearly 100,000 civilians at its bases, officials said.
The U.N. delegation met members of Kiir's cabinet on Tuesday and is scheduled to meet the rebels later in the week.
"We will engage Riek Machar as well, probably tomorrow (Wednesday), and we will deliver a very tough message to him," Powers said