A massive blackout plunged two-thirds of Cuba, including Havana, into darkness on Wednesday after the island's largest power plant shut down unexpectedly.

The outage at the Antonio Guiteras thermoelectric plant, located about 100 kilometers east of Havana, triggered a partial collapse of the National Electric System. State utility Unión Eléctrica (UNE) reported the failure stemmed from a malfunction in the boiler's superheater and leaks, affecting provinces from Pinar del Río in the far west to Camagüey in the center-east. Nearly 7 million of Cuba's roughly 10 million residents lost power, with only the far eastern provinces and the Felton 1 plant in Holguín remaining operational.

By Thursday morning, officials reconnected the grid from Pinar del Río to Guantánamo, though generation stood at only 590 megawatts against a normal capacity of nearly 2,000 megawatts. In Havana, about 36% of the city had power restored, with efforts continuing gradually. The grid remained vulnerable due to low output, and full repairs at Guiteras could take three to four days, according to plant technical director Román Pérez.

Lázaro Guerra, director of electricity for the Energy Ministry, attributed the crisis primarily to fuel shortages. "The current operational situation is fundamentally marked by the fuel shortage in the country," he said. "This shortage, coupled with the power outage at the Guiteras plant, clearly triggered the system failure." When asked about U.S. sanctions, Guerra replied, "Exactly."

Cuba has faced chronic blackouts since early 2024, driven by aging infrastructure, spare parts shortages, and reduced oil imports from allies like Venezuela and Russia. The latest crisis intensified after the U.S. ousted Venezuelan leader Nicolás Maduro in January, curtailing shipments from Cuba's top supplier. Mexico also halted supplies amid U.S. tariff threats. UNE had warned that up to 63% of the island could face outages at peak demand this week.

The blackout disrupted daily life in Havana, where residents relied on solar panels and generators for essentials. Traffic lights failed in some areas, and state television briefly went off air. The U.S. Embassy in Havana issued a security alert, noting disruptions from Camagüey to Pinar del Río with no clear restoration timeline at the time.

Previous incidents include nationwide outages in October 2024 and December 2024-2025 from similar Guiteras failures, as well as storm-related blackouts. Wednesday's event marked the second major western Cuba outage in three months, compounding economic woes like rationed services and food spoilage.