The UN Security Council will vote Thursday on a draft resolution presented by the United States that would give warring sides in South Sudan until June 30 to end fighting or face possible sanctions.
The proposed measure, which was seen by AFP, lists South Sudan's defense minister among six officials who could be put on a UN sanctions blacklist if the sides fail to reach a peace deal.
The draft resolution would require UN Secretary-General Antonio Guterres to report by June 30 whether fighting has stopped and whether the sides have "come to a viable political agreement."
If not, the council "shall consider" imposing the sanctions and possibly an arms embargo within five days, according to the draft resolution.
Diplomats said it remained unclear whether the United States will win the required nine votes in the 15-member council to put in motion the move to punish South Sudan's leaders.
South Sudan won independence from Sudan in 2011, with critical backing from the United States, which remains Juba's biggest aid donor.
But the US administration has grown increasingly frustrated with President Salva Kiir's government as the brutal war grinds on, now in its fourth year.
In an op-ed on South Sudan published this week in the Washington Post, US Ambassador Nikki Haley said: "We have no more time to waste on empty promises."
"By imposing financial and travel restrictions on individuals responsible for threatening the peace, we can ensure they pay a cost for perpetuating violence," she wrote.
The United States last week proposed sanctions against the six South Sudanese officials but amended its proposal following negotiations to add the June 30 deadline.
The proposed sanctions blacklist would target Defense Minister Kuol Manyang Juk for leading attacks on the northeastern town of Pagak that was captured from rebel forces in 2017.
Also listed is cabinet minister Martin Elia Lomuro for threatening the press, obstructing humanitarian aid and impeding the work of the UN peacekeeping mission in South Sudan.
Information Minister Michael Makuei is cited for his role in planning an attack in 2014 on a United Nations compound in Bor and overseeing a campaign to suppress the media.
Former military chief Paul Malong faces possible sanctions for ordering government forces to attack civilians, schools and hospitals and deputy army chief of staff Malek Reuben for overseeing an offensive in 2015.
Also included is Koang Rambang Chol for leading attacks in northern Bieh state and ordering his forces to impede the work of aid workers.
The six would face a global travel ban and assets freeze if the draft resolution is adopted at the meeting scheduled for 3:00 pm (1900 GMT).
Since the start of the war in December 2013, nearly 1.8 million people have been forced to flee their homes and tens of thousands have been killed.
In 2016, Washington failed to win enough votes at the Security Council for the arms embargo and targeted sanctions.
Ethiopia is leading a regional peace effort, hosting talks between the government and rebel groups, but there has been no breakthrough.