On a muggy morning in eastern Havana, a bus crammed with more than 100 sweaty commuters pulls in to a bus stop. The doors open and more passengers press in before – inch by inch – the hydraulic doors groan shut, slowly shunting the new arrivals inside.

“All the buses are coming like this,” said Roberto López, 66, on his way – fingers crossed – to buy biscuits in the city centre.

Bus services throughout Cuba have been slashed in recent weeks as the island grapples with acute petrol shortages caused by US sanctions which target companies and oil tankers transporting Venezuelan petroleum to the island.

Cuba’s president, Miguel Díaz-Canel, has said the island is currently operating with 62% of the petrol it needs, and announced emergency measures to “disrupt the plans of imperialism”. Across the island, production has been cut and stopgaps found, so that fuel can be prioritized for hospitals, schools and food distribution.

Oxen have replaced tractors in sugarcane fields; some bakeries are using firewood to power their ovens. Transport inspectors have been deployed to ensure that anyone driving a vehicle which belongs to a ministry or state enterprise gives fellow citizens a lift.

At the Alamar textile factory – and in offices and factories throughout the island – all machines and lights are switched off between 11am and 1pm. Taking her extended lunch break, Aimee Machu, 52, said the US wants to stem the flow of oil to “extinguish the flame of communism”.

“It they cut the power in my house it’ll be torture,” she laughed, adding with mettle: “But if we have to go through power cuts again, we’ll do it.”

“We’re Cuban,” her colleague Rita Castro, 60, chuckled. “We’re used to this!”

Despite its myriad problems, the Cuban economy has proved resilient when times get tough, according to Pavel Vidal, a former economist at the Cuban Central Bank who now teaches at the Javeriana Cali University in Colombia.

“In normal conditions, Cuba’s centrally planned economy impedes economic growth, progress and innovation,” he said. “But in times of crisis, having a plan to assign resources where they are needed is an advantage.”

The collapse of Venezuela’s oil industry – the result of years of mismanagement, incompetence and, more recently, US sanctions – has seen its oil shipments to Cuba slump, from more than 90,000 barrels a day four years ago to about 40,000 today.

Alberto Font and Iris Ortiz watch a local TV news recording of a speech by Cuba’s President Miguel Díaz-Canel in Havana on Thursday. Photograph: Alexandre Meneghini/Reuters

The current US plan to starve the Cuban economy of oil – which the state department says is necessary to pressure Cuba to stop supporting Nicolás Maduro’s regime – is part of an onslaught on the communist-ruled island unleashed by the Trump administration this year. The US has progressively ratcheted up sanctions against Venezuelan oil and those buying or transporting it since January, culminating in Cuba’s oil import-export company also being placed under sanctions in July.

The three biggest sectors of the island’s economy have all been targeted. The state department is working to delegitimise the island’s main export: the leasing of doctors to other developing countries. In June, the secretary of state, Mike Pompeo, said Cuba’s medical cooperation programmes – to which doctors sign up voluntarily – amount to “human trafficking”.

In June US cruise ships were banned from docking at the island – a major blow to tourism – while in September the cap on remittances people in the US can send to the island was sharply cut back.

The Cuban government insists the situation is “temporary” and has said there will be no return to anything resembling the “Special Period”, the official term for the deep economic crisis Cuba went through after the fall of the Soviet Union, when the average adult lost more than 5kg and getting through the day without electricity was so common that Cubans talked not so much of “power cuts” (apagones) but of “power ons” (alumbrones).

After seeing her country’s economy improve rapidly after the normalisation of US-Cuban relations announced in 2014, Maite Rizo, 26, has watched the deterioration of relations between the two countries with alarm.

“I feel confused, even scared,” she said. “We’ve gone from a period of bonanza to a situation where everything’s gone backwards very quickly. From here on, we don’t know what will happen.”

Throughout the capital, meanwhile, commuters get by as best they can.

“It’s a battle to get to work,” said Nuerca Sánchez, 45, a rumba teacher, while a dozen commuters jostled for spare seats in a car on its way to a state cigar factory. She sees the emergency transport measures as common sense, and is touched when the odd private car stops voluntarily to give people lifts.

“Helping each other isn’t about politics,” she said. “It’s about having heart.”

Under the blazing sun, others take the long view.

Pedro Leocadeo, 64, who is retired, concedes that he might wait hours for a place on a bus. Shimmering in beads of sweat, he sees the sanctions on tankers in the broad sweep of New World history.

“We’ve been in this ever since Hatuey,” he said, invoking the Taíno warrior who in 1511 fled from the island of Hispaniola to Cuba to warn the natives of unscrupulous aggressors from foreign lands.

“We’re like this today; tomorrow things might get better – the following day things might get worse again,” he said. “Today, it all depends on the Yankees.”