A White House push to reinforce a struggling United Nations peacekeeping force in South Sudan encountered stiff resistance this week from its once-reliable ally President Salva Kiir, highlighting Washington’s waning influence in a country it helped create only five years ago.

The United States wants 4,000 new peacekeepers deployed to protect South Sudanese civilians after more than 300 people were killed when violence broke out between government and rebel soldiers in the capital of Juba last month. The uptick in violence came amid the uneasy implementation of a deal creating a transitional government intended to end the country’s brutal civil war.

But South Sudan’s ambassador to Washington, Garang Diing Akuong, told Foreign Policy on Wednesday that the plan amounts to the establishment of a U.N. protectorate in his country, which would undermine its sovereignty. “This proposal means invasion of South Sudan, means recolonization of South Sudan, and means ruling of South Sudan by the U.N.,” Garang said in a telephone call.

The decision by South Sudan to oppose the deployment of the so-called “regional protection force” in Juba to reinforce UNMISS, a mission of 12,000 blue helmets, marked a reversal of a prior commitment it made to accept the U.N. force, according to U.S. officials. But South Sudan countered that the United States cut Juba out of U.N. discussions defining the mandate of the new force.

Anticipating South Sudanese support, the United States on Monday introduced a U.N. Security Council resolution calling for the deployment of the new force in Juba to restore order and take control of the international airport, and threatened to impose an arms embargo if those efforts were opposed. But negotiations over the text became quickly mired in acrimony after Juba announced its opposition.

South Sudan’s decision has divided the Security Council. The United States and its European allies want to press ahead with a vote on the new force by Friday, while Egypt, Russia, and Angola have been far more receptive to South Sudan’s concerns. Egypt has seized on the split, offering to play a role in mediating a resolution of the diplomatic standoff.

South Sudan’s independence capped decades of bipartisan efforts by Republican and Democratic leaders to liberate the largely Christian and animist people from the predominantly Muslim Sudanese government in Khartoum. A final 2005 peace deal, the U.S.-brokered Comprehensive Peace Agreement, formally ended a decades-long war that left more than 2 million people dead.

With tremendous support from the United States, South Sudan gained independence in 2011, spurring hope for peace in a region rocked by the bloody split from the north. But a power struggle between South Sudan’s new leaders, President Salva Kiir and then-Vice President Riek Machar, plunged the country into a civil war in December 2013.

The two rivals signed a peace deal under intense international pressure last August, but some of the conflict’s worst violence took place in the months that followed. Machar finally returned to the capital of Juba on April 28, but the already shaky transitional government essentially collapsed in July, as government and opposition forces battled in Juba. Forces loyal to Kiir ultimately attacked U.N. installations housing tens of thousands of civilians, in some cases raping civilians in front of peacekeepers who reportedly stood by and watched. The opposition also claimed government troops bombed Machar’s makeshift camp, forcing him to flee the capital after months of negotiations that allowed for his April return.

The opposition has spoken out in support of additional peacekeepers. Reath Muoch Tang, a former member of the South Sudanese parliament who now serves as a representative for the opposition in Washington, D.C., told FP in a phone call on Wednesday that Machar will not return to Juba until Kiir’s forces no longer control the capital.

“Sovereignty is for the government to protect its people and give them a parliament,” he said. “The sovereignty they’re talking about is that they should be allowed to kill and allow their people to rape women.”

The scale of violence amid this political disorder has raised doubts about the ability — and the willingness — of U.N. blue helmets to protect civilians, even in U.N. compounds. Since the fighting started in December, 2013, more than 50,000 people have been killed and another 2 million people displaced, including more than 180,000 who are seeking protection in six U.N. compounds. A U.N. board of inquiry this month faulted the U.N.’s response to an attack likely carried out by government forces and allied militias on a U.N. compound in the northeastern city of Malakal, which resulted in 30 deaths and 123 injuries.

The U.N. shortcomings in Malakal and elsewhere have contributed to the United States’ push for more peacekeepers. On Friday, an East African bloc of countries, known as IGAD, issued a statement from Addis Ababa, Ethiopia, calling on the Security Council to authorize a regional protection force to help bolster the U.N. operations in South Sudan. The statement noted that the South Sudan had “accepted in principle” the idea of deploying such a force. But it also insisted that it would have to negotiate the composition and mandate of the new force with countries providing troops.

But with the U.N. peacekeeping mission’s mandate set to expire Friday, the United States moved quickly to table a resolution defining the new force’s mandate. The U.S.-drafted resolution circulated on Monday demands South Sudan’s warring parties immediately cease fighting throughout the country and authorizes the new regional protection force to use “all means necessary” — diplomatic shorthand for the use of force — to secure key installations in Juba, including the airport, protect civilians and U.N. installations, and help implement an agreement to redeploy government troops outside of Juba.

But there were signs earlier this week that South Sudan, after seeing the U.S.-drafted resolution, was deeply uneasy over the plan. On August 8, South Sudan’s cabinet of ministers issued a statement expressing “anxiety and serious concern” over the U.S. draft resolution. The resolution, according to the statement, would make the U.N. representative the “de facto president of the Republic of South Sudan.”

The United States has already made concessions designed to win Kiir’s support. For instance, Washington agreed to strip out a provision that called on South Sudan’s transitional government to prosecute individuals responsible for obstructing humanitarian aid and interfering with the U.N.’s ability to carry out its mandate, according to an internal draft revision obtained by FP.

There is broad support among key American allies, including Britain, France, Spain, and New Zealand, for the imposition of an immediate U.N. arms embargo.

But Susan Rice, the U.S. national security advisor, has been reluctant to hit a long-time friend and ally with such an embargo, citing the likely ineffectiveness of such measures in a region already awash with weapons. Instead, the U.S. has continued to dangle the threat of a weapons prohibition for nearly two years without ever acting on it.

The latest draft before the council only threatens to impose an arms embargo if South Sudan blocks the deployment of thousands of new peacekeepers, and a new vote of the Security Council would be required to impose the arms ban, which human rights advocates say makes the White House’s threats self-defeating.

“The U.S. National Security Council remains reluctant to pull the trigger on a long overdue arms embargo because of the mistaken hope that South Sudanese leaders will change their behavior based on threats alone,” Akshaya Kumar, Human Rights Watch’s deputy U.N. director, told FP. “Threats ring hollow if they are never followed up by action.”

But John Prendergast, a longtime friend of Rice who founded the Enough Project, a Washington-based nonprofit organization focused on genocide prevention, said that Rice’s “overwhelming priority right now is to deploy international forces that can play a role in protecting civilians in Juba.”

“I believe she felt that threatening an arms embargo was better as leverage for that force than actually imposing an embargo, which could drive the Juba government further into an intransigent position regarding the deployment of the force,” he added.