The pause in activity arrives as global copper markets grapple with tightening supply and volatile pricing, with U.S. futures climbing 17% since the start of the year. Rio Tinto, which holds a 66% stake in the project, has been aggressively expanding underground extraction to reach high-value deposits located deep beneath the surface, moving beyond the open-pit operations that have defined the site since 2011.

Production momentum remains high despite the current setback, with the company reporting a 29% increase in year-to-date output earlier this month. The Mongolian government maintains a 34% interest in the mine, which is projected to become the world’s fourth-largest copper operation by 2030. Management has yet to provide a timeline for resuming underground work, stating only that the suspension will remain in effect until the safety assessment concludes.