Cuba was plunged into darkness on Sunday night after the country’s national electricity grid suffered another major collapse, leaving millions of residents without power.

The latest outage affects the Caribbean nation of roughly 10 million people and adds to a series of widespread blackouts that have disrupted daily life in recent weeks. It marks the fourth nationwide power failure in about a month, highlighting the deepening challenges facing the country’s energy sector.

State-run electricity operator Unión Eléctrica confirmed the collapse of the grid in brief statements shared on social media but did not immediately provide details on the cause of the failure or when electricity would be fully restored.

Cuba’s power system has been under mounting pressure due to persistent fuel shortages and ageing infrastructure. The situation has worsened following the disruption of key fuel supplies, including Venezuelan oil, after recent U.S. measures targeting energy shipments. Fuel imports from Mexico have also reportedly declined amid increased pressure from Washington.

As authorities struggle to stabilise electricity generation, the government has begun easing restrictions in parts of the energy sector. Havana recently approved its first foreign-supported fuel import initiative and expanded access for nearly 200 domestic businesses to participate in wholesale fuel distribution in an effort to improve supply.