South Sudan has been at war since 2013, when President Salva Kiir accused then-deputy Riek Machar of plotting a coup.
A United States-drafted resolution won the minimum nine votes needed, while six member states abstained, wary of voting for the measure amid regional attempts to revitalise the South Sudan peace process.
US Ambassador to the UN Nikki Haley said the adoption of the resolution was necessary “to stop the violence, we need to stop the flow of weapons that armed groups are using to fight each other and to terrorise the people”.
How the Security Council voted
Ivory Coast, France, Kuwait, Netherlands, Peru, Poland, Sweden, United Kingdom, United States
Abstained from voting:
Bolivia, China, Equatorial Guinea, Ethiopia, Kazakhstan, Russia
But South Sudan’s UN Ambassador Akuei Bona Malwal told the council the resolution would “undermine peace” and was “a slap in the face of those organisations who are trying to bring peace in South Sudan”.
Ethiopia’s UN Ambassador Tekeda Alemu told the council before the vote that imposing the arms embargo would undermine the peace process and that the African Union and East African regional bloc IGAD believe “now is not the appropriate time for taking such measures.”
China’s UN Ambassador, Ma Zhaoxu, meanwhile said the council should have listened to African leaders on the issue.
In December 2016, a similar resolution was brought before the UN Security Council by the US, but it did not receive enough votes to pass at the time.
Over the years, the conflict has expanded and fighting has intensified with more than a dozen warring factions.
Several ceasefires have previously been violated by the warring parties.
South Sudan had originally scheduled elections this year, but the bloody conflict has made the timetable impossible as government and the opposition try to thrash out details of the peace deal.
The country’s parliament voted in 2015 to extend Kiir’s term by three years, after elections due to be held in June of that year were called off.
Kiir’s transitional term was expected to end in July this year.
But South Sudan’s parliament has voted to extend Kiir’s current tenure by three years, raising objections from the opposition, which called the move illegal.
The civil war has killed tens of thousands of people and forced millions to flee their homes, triggering a humanitarian crisis.
Seven million South Sudanese, more than half of the population, will need food aid in 2018, according to the UN.
It has also cut the country’s crude oil production, which the government depends on for revenue, with output at less than half its prewar level of 245,000 barrels a day.