“Chinese President Xi Jinping wants to restore China to greatness. He wants to make it the sole superpower in the world. I believe he is doing it,” Canavero said.

Canavero decried the unwillingness of the US or Europe to host the surgery.

“No American medical institute or centre would pursue this, and there is no will by the US government to support it,” he said.

He would not reveal the identities of the Chinese donor or recipient. The donor will be the healthy body of a brain-dead patient matched for build with a recipient’s disease-free head.

Canavero estimates the procedure will cost up to US$100 million and involve several dozen surgeons and other specialists.

He will simultaneously sever the spinal cords of the donor and recipient with a diamond blade. To protect the recipient’s brain from immediate death before it is attached to the body, it will be cooled to a state of deep hypothermia.

The recipient and donor will be in a sitting position to facilitate what’s expected to be more than 24 hours of work to separate and then reconnect vertebral bones, jugular veins, the trachea, oesophagus and other neck structures. Machines will help the recipient breathe and pump blood through the body. The patient will be kept in a drug-induced coma.

Michael Sarr, a former surgeon at the Mayo Clinic in Rochester, Minnesota, and the editor of the journal Surgery, said Canavero’s procedure is radical.

Doctors “have always been taught that when you cut a nerve, the ‘downstream side’, the part that takes a signal and conducts it to somewhere else, dies,” he said. “The ‘upstream side’, the part that generates the signal, dies back a little – a millimetre or two – and eventually regrows. As long as that ‘downstream’ channel is still there, it can regrow through that channel, but only for a length of about a foot.”

This is why, he said, if you amputate your wrist and then re-implant it and line the nerves up well, you can recover function in your hand. But if your arm gets amputated at the shoulder, it will not be re-implanted because it will never lead to a functional hand.

“What Canavero will do differently is bathe the ends of the nerves in a solution that stabilises the membranes and put them back together,” Sarr said. “The nerves will be fused, but will not regrow. And he will do this not in the peripheral nerves such as you find in the arm, but in the spinal cord, where there’s multiple types of nerve channels.”

There has been some success using Canavero’s proposed technique on mice and dogs. In one example, a dog walked after six weeks, albeit with an awkward gait. “Based on the classic thinking about how nerves regenerate it was unbelievable,” Sarr said.

Canavero said his team has “rehearsed” his technique with human cadavers in China, but there are otherwise no known human trials. He said the 18-hour operation on two corpses showed it was possible to reconnect the spinal cord and blood vessels. Before the full transplant takes place, two brain-dead patients will undergo the surgery.

Most medical experts say it is a long shot, but even if the operation works the biggest obstacle may not be the science itself, but whether it should happen at all.

“There are too many risks at this point to go ahead with it,” said Assya Pascalev, a biomedical ethicist at Howard University in Washington. “We don’t have enough data with animal models, sufficient published and peer-reviewed results, and particularly data about mobility and morbidity on the animals that have had the procedure.”

Pascalev said that any groundbreaking procedure is certain to face objections and scepticism, and requires a leap of faith.

Canavero dismissed any concerns.

“Western bioethicists needed to stop patronising the world,” he said. He added that China’s receptiveness to hosting the surgery reflected its determination to replace the US as the world leader in all fields.