MEXICO CITY (AP) — As the United States prepares to seize control of Venezuelan oil and the administration of U.S. President Donald Trump hardens its stance toward Cuba, Mexico has emerged as a key fuel supplier to Havana.

It’s a role that could further complicate already strained relations with the Trump administration, even though the Mexican government insists that exports to the island have not increased.

Mexican President Claudia Sheinbaum acknowledged on Wednesday that “with the current situation in Venezuela, Mexico has become an important supplier” of crude oil to Cuba, but asserted that “no more oil is being sent than has been sent historically; there is no specific shipment.”

She added that those shipments are made via “contracts” or as “humanitarian aid,” but offered no concrete figures on the number of barrels exported.

‘The blackouts are going to intensify’

Following the 1959 revolution that toppled dictator Fulgencio Batista, the U.S. imposed a trade embargo on Cuba in response to the nationalization of American-owned property. Under the embargo — long denounced by many countries, including Mexico — Cubans have suffered economic and energy crises, driving hundreds of thousands of Cubans to migrate, especially to the United States.

Blackouts that last up to eight hours and long lines at gas stations are routine across Cuba.

José Martínez, a 65-year-old former construction worker and resident of Old Havana whose power goes out daily, said the upheaval in Venezuela will impact Cuba.

“The blackouts are going to intensify with all this,” he said, adding that he believes the U.S. attacked because they want Venezuela’s oil. “They own the world.”