US Secretary of State Marco Rubio said that Cuba's leadership must change as Washington renewed an offer of $100 million (€85 million) in aid if the communist-run island agrees to cooperate.
Cuba has been suffering severe economic tumult led by an energy shortage that plunged 65% of the country into darkness on Tuesday.
Cuba's leaders have blamed US sanctions but Rubio, a Cuban-American and vociferous critic of the government established by Fidel Castro, said the system was to blame including corruption by the military.
"It's a broken, non-functional economy, and it's impossible to change it. I wish it were different," he told Fox News host Sean Hannity on Air Force One as he travelled with President Donald Trump to China.
"We'll give them a chance. But I don't think it's going to happen."
