A power outage struck most of Cuba, including the capital of Havana, the country's national electricity union UNE said Wednesday, as the island's communist-run government faces increasing pressure from the Trump administration.

Cuba has experienced a series of major blackouts in recent years, even before the U.S. cut off oil shipments to the Caribbean's largest island.

Cuba's government has attributed its economic crisis to decades of economic sanctions from the U.S.

A more recent scarcity of oil from Venezuela and Mexico due to U.S. pressure has worsened existing shortages.

The UNE electricity union said it was working to restore services, and that the blackout affected the island from the central province of Camaguey to Pinar del Rio in the far west.

The Felton 1 thermoelectric power plant, located in Holguin province in eastern Cuba, remains online and recovery protocols have been activated, Cuba's energy ministry said.

Venezuela, Cuba's top oil supplier, has not sent shipments since December. Its president, Nicolas Maduro, was captured in a U.S. attack on its capital early January, after which the U.S. has controlled the country's oil exports.

Mexico said it would halt supplies after the U.S. threatened tariffs on countries supplying Cuba with oil.

The power cuts have caused the government to ration key services.