The Trump administration has put on hold a deal by a Florida energy trading company to send to Cuba one of the largest cargoes of fuel from the United States in decades.

The company, Vanguard Energy, said this week that it had struck an agreement with the Cuban authorities allowing it to send 250,000 barrels of gasoline and diesel from a Texas refinery to the island nation and lease Cuban government facilities to store the fuel upon arrival.

But when details of the deal became public in recent days, the State Department quickly intervened, making it clear that Vanguard required explicit approval from the U.S. authorities to proceed.

“Vanguard Energy has not received any U.S. license for this transaction,” the State Department said in a statement. “The Trump administration’s sanctions remain in effect absent specific guidance or licensing to the contrary.”

The Trump administration’s move to put the deal on ice reflects how it is trying to apply greater pressure on Cuba’s government by restricting the flow of oil to the country, which has been grappling for months with dwindling fuel supplies.

The energy crisis in Cuba has grown more acute since January, when U.S. forces deposed and captured Nicolás Maduro, the former leader of Venezuela, which had long supplied Cuba with a lifeline of subsidized oil.

The Trump administration forced Venezuela to halt such shipments and made it harder for other nations to supply Cuba with oil, part of a broader effort aimed at coercing Cuba’s government to remove its leader and force political and economic change.

But U.S. officials also carved out an exception allowing companies to send relatively small amounts of fuel to Cuba’s private sector, as well as religious and humanitarian organizations.

Vanguard Energy, a trading company which specializes in supplying fuel in the Caribbean and Latin America, had been operating within this new framework, sending small tanks of fuel to Cuba.

In May, the company reached a deal with the Cuban authorities that could have expanded these operations by shipping fuel to Cuba in much larger oil tankers, allowing greater volumes of fuel to reach the nation and potentially bringing gas prices down.

The agreement opened the way for Vanguard to send an initial cargo of about 250,000 barrels of refined fuels to Cuba, enough to meet about a week and a half of demand in the country, The Miami Herald and Bloomberg reported this week.

That cargo would have amounted to one of the largest shipments of fuel from the United States to Cuba since a trade embargo was imposed in the 1960s.

But the State Department’s position now effectively pauses the deal. Going even further, the United States announced additional sanctions on Thursday on Cuba’s national oil company, Cupet. The sanctions effectively make it harder to make energy deals in Cuba which are not authorized by the United States.  

Matthew Klann, Vanguard’s president, said the company was continuing to work with the U.S. authorities to try to obtain the required approvals to proceed.

“Vanguard remain committed to conducting its business in a manner consistent with U.S. law, national interests and long-term policy objectives,” Mr. Klann said in a telephone interview.

For now, only a trickle of oil is reaching Cuba.

The energy shortage, together with hardened U.S. sanctions, has created a humanitarian crisis, including an increase in children dying because doctors cannot access essential medicines, the United Nations said this week.

As the crisis grinds on, the U.S. authorities have stepped up pressure on Cuba’s leadership.

Defense Secretary Pete Hegseth traveled on Wednesday to the U.S. Navy base on the island at Guantánamo Bay, where he warned Cuba against trying to obtain weapons capable of reaching either U.S. soil or the base, in the southeastern portion of the island.

U.S. Blocks Deal by Florida Company to Supply Fuel to Cuba