New York: The UN Security Council took vigorous action Friday to greatly strengthen a peacekeeping force in South Sudan, the world’s youngest country, ravaged by civil war and suffering for nearly three years.

A resolution, passed by an 11-0 vote with four abstentions, basically gives the United Nations far more authority in South Sudan, backed by lethal force if needed, to protect civilians and to pressure armed antagonists in the conflict - including government soldiers. It also threatens to impose an arms embargo on the African country.

The Security Council’s approval came as the mandate of the current peacekeeping operation, known as the UN Mission in South Sudan, or UNMISS, was about to expire. UNMISS has not been effective, as a peace agreement has been repeatedly ignored.

The Security Council resolution, sponsored by the United States, represents an unusually robust action by the Council, invoking its rarely used coercive power to militarily intervene when international peace and security are considered to be threatened.

South Sudan’s government opposed the strengthened peacekeeping mission, raising the possibility of clashes between the country’s armed forces and foreign soldiers deployed there by the UN

Under the resolution, the UN mission will be extended for at least three months, and a new 4,000-soldier “regional protection force” will be deployed in South Sudan’s capital, Juba, and other strategic locations, including the airport.

The new force represents an increase of more than 30 percent in armed personnel for the UN mission of 12,000 troops, which has been unable to stop episodic bouts of killing and abuses, including widespread rape, by both government forces and rebel factions.

UN soldiers and aid workers have been repeatedly harassed and attacked, and in some cases killed. Thousands of South Sudanese civilians, fearing for their lives, have been living in UN facilities in Juba and other locations.

The resolution specifies that the new force, which diplomats said would mostly be drawn from neighboring countries, will be authorised to “promptly and effectively engage any actor that is credibly found to be preparing attacks, or engages in attacks, against United Nations protection of civilians sites, other United Nations premises, United Nations personnel, international and national humanitarian actors, or civilians.”

The resolution does not impose an arms embargo on South Sudan, as Secretary-General Ban Ki-moon and some outside advocates, including international rights groups, had wanted.

But in what was intended as a coercive step, the resolution allows an arms embargo to be imposed if the government does not cooperate.

The resolution’s failure to achieve a unanimous approval of the 15-member Security Council partly reflected the difficulties it has often faced in deciding on any action involving the use of military force.

Russia, China, Egypt and Venezuela, the Council members that abstained, had criticised some provisions in the resolution. Russia and China in particular have been reticent to take actions that they view as incursions on another country’s sovereignty.

Still, the Russians and Chinese did not feel strongly enough to exercise their veto power, which they both have as permanent Security Council members.

South Sudan’s promise as a newly independent state in 2011 devolved into civil war two years later, leaving tens of thousands dead and more than 2.3 million people displaced.

Soldiers loyal to President Salva Kiir - who belongs to the Dinka ethnic group, South Sudan’s largest - battled troops led by Riek Machar of the Nuer ethnic group, which is believed to be the second largest.

Troops on both sides committed human rights abuses against civilians on a devastating scale, UN human rights officials and other groups found.

A peace deal officially ended the fighting last year. Machar, who had served as vice president before he was dismissed in 2013, agreed to become Kiir’s deputy again and returned to Juba in April.

But then fighting broke out again between the two sides on July 7, killing hundreds. Machar’s residence was destroyed, and he fled the capital. He has refused to return to Juba unless more international troops are deployed.

Kiir has argued that the 12,000 troops from the UN mission already stationed in the country are sufficient.