JUBA, South Sudan — The U.N. Security Council is expected to arrive in South Sudan on Friday for a rare visit to the troubled nation on the edge of renewed civil war.

The trip comes amid tensions between South Sudan and the United States, its former champion who now threatens to cut off aid.

At the center of the visit is a council resolution approved last month to send 4,000 additional peacekeepers to secure the capital, Juba, a foreign ministry spokesman, Mawien Arik, told The Associated Press. Hundreds were killed in Juba when government and rebel forces clashed in July, and rebel leader Riek Machar fled the country and is now in Sudan.

The diplomats must balance two main goals: avoiding further bloodshed in the country, a priority of the United States; and respecting South Sudan’s sovereignty, a priority of Russia, China, and Egypt.

They are expected to meet with President Salva Kiir and visit U.N. sites where tens of thousands of South Sudanese have sheltered from the fighting, amid allegations that U.N. peacekeepers in some cases have not done enough to protect them.

“The Security Council is going there to say, ‘What’s next? Are we going to get any cooperation out here?'” said Princeton Lyman, the former U.S. envoy for Sudan and South Sudan. “It’s kind of a fact-finding mission.”

The trip is also the latest chapter in the brief but complicated relationship between the United States and South Sudan.

Government spokesman Michael Makuei has called a U.S.-proposed plan to send in additional peacekeepers “a new colonialism.”

Americans were targeted in a rampage by South Sudanese troops at a Juba hotel compound popular with foreigners a few days after the fighting erupted in July, with witnesses telling the AP that people were gang-raped, beaten and forced to watch a local journalist be shot dead.

Meanwhile, the U.S., which says it is the largest humanitarian donor to South Sudan, has threatened to cut its aid to the country if the government does not take positive steps to peace. Just over a year has passed since South Sudan’s warring sides agreed to a peace deal under intense international pressure, but both sides “violated the agreement from day one,” according to Festus Mogae, the top diplomat in charge of monitoring the agreement.

“I hope and pray the U.S. remains our ally and friend,” Kiir told lawmakers on Aug. 15.

The tension between the two countries is a far cry from the key role that the U.S. played to help South Sudan achieve independence in 2011 from Sudan.

“I have known (Kiir) for years,” said U.S. Congressman Chris Smith, who met with the president last weekend in Juba. “We had the highest of hopes for this fledgling democracy of five years and celebrated when (South Sudan) became independent.”

But in December 2013, South Sudan erupted into a civil war between Kiir and Machar, who had been vice president. Tens of thousands of people died, more than two million were displaced and both sides have been accused of war crimes.

There are already 12,000 U.N. peacekeepers in South Sudan, who have been criticized for failing to protect civilians. The additional 4,000 peacekeepers are meant to protect civilians but will only be deployed around the capital where government troops, who have been accused of raping and looting civilians, are located.

When the U.N. recently went to investigate reports of bodies surfacing in a river and civilians being arrested for supporting the opposition in the southern city of Yei, the government blocked it numerous times, Shantal Persaud, a spokeswoman for the U.N. in South Sudan, told the AP.

“South Sudan is a textbook case of how not to deal with a humanitarian tragedy,” said one former diplomat based in South Sudan who spoke on condition of anonymity to preserve their country’s relations.