As President Donald Trump signals possible action, experts say Cuba has no clear successor while Raúl Castro, 94, remains a significant influence on the communist country.

The U.S. and Cuban governments have been at odds since the conclusion of the Cuban Revolution 67 years ago. Yet despite pressure, embargoes and various CIA plots, the communist government in Havana has resisted the wishes of its very powerful neighbor separated by just 90 miles (145 kilometers) of water.

The fuel-starved Caribbean island is facing its biggest test since the collapse of the Soviet Union under a U.S. oil blockade.

Cuba's power grid collapsed for the second time in a week, leaving millions without power amid a U.S. blockade squeezing oil and other resources.

The Treasury Department added Cuba to a list of countries restricted from taking delivery of Russian oil after a tanker of the fuel appeared to be headed to the island, which is under a US naval blockade.

The Cuban government denied the U.S. embassy in Havana’s request to import fuel to keep generators running for the building, as the country experiences island-wide blackouts amid a dire oil shortage caused by the Trump administration.

By Daniel Trotta and Dave Sherwood HAVANA, March 16 (Reuters) - Cuba on Monday extended an invitation to Cuban Americans and other exiles living abroad to invest in and own businesses on the island, saying the "doors are open" to a community that has traditionally agitated for harsh economic sanctions against the Communist government.

The U.S. Treasury excludes Cuba from a temporary Russian oil waiver as the Anatoly Kolodkin tanker approaches, raising tensions over sanctions and fuel access

Cuba is open to having a fluid commercial relationship with U.S. companies" and "also with Cubans residing in the United States and their descendants," Deputy Prime Minister Oscar Pérez-Oliva Fraga said in an interview in Havana.

On Monday Cuba was plunged into an island-wide blackout affecting 11 million people after a "complete disconnection" of its electrical system, officials said, amid a worsening fuel shortage.

Videos circulating on social media show residents in Santiago de Cuba banging pots and pans — a form of protest known as “cacerolazo” — as they demand electricity and relief from the ongoing crisis.

The White House’s campaign has included an executive order threatening tariffs on countries that send oil to Cuba.