The U.N. Security Council is demanding an immediate end to fighting in South Sudan and threatening to consider an arms embargo and sanctions to prevent parties from violating a December cease-fire agreement.

A U.S.-drafted resolution, adopted unanimously Thursday, also expresses the council's intention to consider sanctions "against those who take actions that undermine the peace, stability, and security of South Sudan."

The resolution extends the mandate of the U.N. peacekeeping force in South Sudan until March 15, 2019 and maintains the 17,000 troops there, which includes a regional protection force of up to 4,000 troops and 2,101 international police personnel.

South Sudan is in its fifth year of fighting. The conflict has killed tens of thousands and displaced millions, but shows no signs of ending.