Cuba's national energy grid suffered a major failure early Thursday that severed power to the island's eastern provinces, authorities said, as residents in the capital Havana faced ongoing blackouts. The failure came as a U.S. delegation visited Cuba Thursday and met with Cuban government officials. 

Cuba's aging power grid has eroded in recent years as it faces a prolonged economic crisis, recently made worse by a U.S. energy blockade of the island, where daily life can be an ordeal for many of the country's 10 million people.

The state-run Electric Union said the collapse had stripped power from all eastern provinces from Guantánamo to Ciego de Ávila, and that crews were working to restore power, but it did not give an estimate for how long it would take.

The previous day, Cuban President Miguel Díaz-Canel had described the energy situation as "tense" after supplies of oil delivered by a Russian vessel in late March ran out. Cuba produces barely 40% of the fuel it needs to power its economy.

Russia announced plans to send a second fuel ship to Cuba in early April. According to Russian news reports, the oil tanker left the Russian Baltic port of Vysotsk in January, but has been stuck in the same place in the Atlantic Ocean for the last several weeks.

According to the Reuters news agency, Cuban Energy Minister Vicente de la O Levy said Wednesday on state-run media that the island has "absolutely no fuel, and absolutely no diesel...We have no reserves."  

Mexican President Claudia Sheinbaum said Wednesday during a news conference that Mexico had also sent a ship carrying humanitarian aid to Cuba, although she told a reporter that because Russia was sending oil, "We are focusing our efforts on providing other forms of humanitarian support."

She decried the U.S. blockade, saying, "We do not agree with it. We have never agreed with it, not since the very moment it was first imposed in 1962. Therefore, we will continue to send humanitarian aid to a people in need."

Power outages in Havana, where authorities have been rationing power, stretched to 24 consecutive hours on Thursday.

On Wednesday evening, Associated Press journalists saw residents in numerous neighborhoods banging pots and pans and setting fire to trash cans to protest the blackouts. Hours later, Energy and Mines Minister Vicente de la O Levy appeared on Cuban television to describe the energy situation as "critical."

The Cuban government said in a social media post that a U.S. delegation that included CIA Director John Ratcliff visited the island Thursday and held a meeting with Cuba's interior department.

"The elements provided by the Cuban side and the exchanges held with the U.S. delegation made it possible to categorically demonstrate that Cuba does not constitute a threat to the national security of the U.S., nor are there legitimate reasons to include it on the list of countries that, allegedly, sponsor terrorism," the Cuban government wrote. 

The State Department said Thursday it has offered "$100 million in direct humanitarian assistance to the Cuban people that would be distributed in coordination with the Catholic Church and other reliable independent humanitarian organizations." 

"The decision rests with the Cuban regime to accept our offer of assistance or deny critical life-saving aid and ultimately be accountable to the Cuban people for standing in the way of critical assistance," the State Department added.

The Cuban Embassy in the U.S. on Thursday confirmed the U.S. formally offered $100 million in aid, but said it "remains unclear whether this aid will be in the form of cash or in-kind assistance, and whether it will be directed toward the people's most urgent needs at this time, such as fuel, food, and medicine."

"Even taking into account the incongruity of this apparent generosity from a party that subjects the Cuban people to collective punishment through an economic war, the Cuban government does not, as a matter of practice, reject foreign aid offered in good faith and with genuine aims of cooperation, whether bilateral or multilateral," the embassy said. 

The embassy said it hopes the aid offer would be "free of political maneuvering," adding, "The best assistance the U.S. government could provide to the noble Cuban people at this time—and at any time—is to de-escalate the energy, economic, commercial, and financial blockade measures."

Cuban President Miguel Díaz-Canel similarly posted on social media, "If there is truly a willingness on the part of the United States government to provide aid in the amounts it announces and in full conformity with the universally recognized practices for humanitarian assistance, it will encounter no obstacles or ingratitude from Cuba."

"The damage could be alleviated in a much easier and more expeditious way by lifting or easing the blockade," he added.

Cuba's power grid is crumbling, but the government has also blamed the outages on U.S. sanctions after President Trump in January warned of tariffs on any country that sells or provides oil to Cuba. The Trump administration has demanded that Cuba release political prisoners and move toward political and economic liberalization in return for a lifting of sanctions.

The blackouts have led to reduced work hours and food spoilage as refrigerators stop working. In some cases, hospitals have canceled surgeries.