The Russian tanker Anatoly Kolodkin, carrying a "humanitarian" shipment of 100,000 tonnes of crude oil, has arrived in Cuba, Interfax news agency reported on Monday, citing the Russian Ministry of Transport.
It said the ship was currently expected to offload the cargo at the port of Matanzas.
LSEG ship-tracking data showed the vessel moving along Cuba's northern shore after US President Donald Trump signalled he was reversing course on blocking oil shipments to Cuba on Sunday, saying he had "no problem" with any country sending in crude to the Caribbean country.
Cuba needs imported fuel oil and diesel to generate power and avoid more outages while petrol sales remain strictly rationed.
The US cut off Venezuelan oil exports to Cuba after toppling Venezuelan President Nicolas Maduro on January 3 and Trump had threatened to slap punishing tariffs on any other country that sent crude to Cuba.
Mexico, the largest supplier to Cuba along with Venezuela, then halted its shipments.
As a result, Cuba has not received an oil tanker in three months, according to President Miguel Diaz-Canel, exacerbating an energy crisis that led to a series of blackouts across the country of 10 million people.
(Reporting by Marina Bobrova and Vladimir Soldatkin; Editing by Guy Faulconbridge and Kate Mayberry)