The first mass anti-government protests in decades in Cuba were partially triggered by energy shortages amid a tighter blockade imposed by former U.S. President Donald Trump, according to the island’s communist leadership.

The discontent is due to “economic asphyxiation” as energy shortfalls force the government to slow economic output and resort to blackouts, President Miguel Diaz-Canel said Monday, at a press conference. He also blamed surging COVID-19 on the island and “Miami’s conservative Cuban-American mafia” for fueling the unrest.

During the protests on Sunday, there were outbreaks of looting and a police car was flipped over, he said. Energy supplies were hit by Trump’s imposition of a stricter embargo in 2017, which has been continued by President Joe Biden, Diaz-Canel said.

Images on social media showed chanting crowds in Havana, the provincial town of San Antonio de los Banos and elsewhere. Large mobilizations against the regime are rare on the tightly-controlled island, which strictly curbs dissent.

Cuba has been under single party rule since its 1959 revolution, and has recently faced growing hunger after its economy was hit by a slump in tourist revenue during the pandemic. The government last year introduced emergency economic reforms in response to the downturn, including eliminating some subsidies, adjusting prices and wages, and ending the dual currency system.

Diaz-Canel recognized there were “legitimate” reasons for Cubans to be dissatisfied, but he also said the protests were part of a a U.S.-backed “unconventional war,” like the one he said had led to protests in Venezuela.

Biden said that the proteters are “bravely asserting fundamental and universal rights.”

“We stand with the Cuban people and their clarion call for freedom and relief from the tragic grip of the pandemic and from the decades of repression and economic suffering to which they have been subjected by Cuba’s authoritarian regime,” he said.

Mexican President Andres Manuel Lopez Obrador called on the U.S. to end the “unjust” embargo, and offered to send medicine, vaccines and food to Cuba if its government requests aid.