A sudden flare-up of fighting in Yemen in early December has thrust the country’s oil economy back into the center of a decade-long conflict that has already produced one of the world’s worst humanitarian crises. 

In a rapid campaign, the Southern Transitional Council (STC) rolled into the eastern provinces of Hadramout and Mahra, officially claiming control of the regions by Dec. 11. The move dealt a blow to Yemen’s internationally-recognized government more than a decade after the country’s civil war began. 

The offensive marked more than just a battlefield gain. The STC’s advance positioned the southern separatists to control roughly 80% of the country’s oil wealth and upended Yemen’s loose, fragile coalition of anti-Houthi forces at a moment when the conflict’s formal frontlines are largely frozen. 

The advance also risks reigniting wider fighting and could further draw Gulf powers into acrimonious competition. Fresh clashes have exposed cracks in the relationship between Saudi Arabia and the United Arab Emirates, which has supported the STC, while Riyadh backs rival factions and provides crucial financial backing to the Internationally Recognized Government (IRG).