The rescue operation to get Venezuelan opposition leader and Nobel laureate María Corina Machado out of Venezuela involved disguises, two boats through choppy seas and a flight, the man who says he led it told the BBC.

Dubbed Operation Golden Dynamite, the dangerous journey was cold, wet and long – but the “formidable” Machado didn’t complain once, said Bryan Stern, a US special forces veteran and founder of the Grey Bull Rescue Foundation.

“The seas are very rough. It’s pitch black. We’re using flashlights to communicate. This is very scary, lots of things can go wrong.”

Despite the risks, they didn’t. Machado arrived safely in Oslo, Norway to collect her Nobel Peace Prize just before midnight on Wednesday.

Machado had been living in hiding in her own country since Venezuela’s widely disputed elections last year, and hadn’t been seen in public since January. Her grown-up children, who she hadn’t seen in two years, were in Oslo to greet her.

Grey Bull specialises in rescue missions and evacuations, especially from conflict and disaster zones. A representative from Machado’s team confirmed to CBS News, the BBC’s US media partner, that the organisation was behind her rescue operation.

Mr Stern said that Grey Bull had been building up a presence in the Caribbean, including inside Venezuela and the neighbouring island of Aruba, for months to get ready for potential operations in Venezuela.

“We’ve been building infrastructure on the ground in Venezuela designed to get Americans, allies and Brits and other people out should the war in Venezuela start,” he told the BBC.

Speculation has been mounting over possible US military action against Venezuela, after US President Donald Trump called on President Maduro to leave office, accusing him of sending narcotics and murderers to the US.

Mr Stern said the challenge in this case was getting somebody out who is as well-known as María Corina Machado – a household name in Venezuela for the opposition.

None of the infrastructure his firm had built up in the country, he said, was “designed for the second most popular person in the damn country with a target on her back.”

When he was first put in contact with Machado’s team, they did not initially disclose her identity, but Mr Stern said he was able to guess.

When they got in touch with him in early December, through a contact who knew Machado’s team, it was apparently the second attempt to get her out of Venezuela, after an initial plan “didn’t go well,” Mr Stern said.

The operation was dubbed “Golden Dynamite” because “Nobel invented dynamite” and Machado was trying to get to Oslo to accept the Nobel Peace Prize award.

Matters moved quickly. Mr Stern said he spoke with the team on a Friday, they deployed on the Sunday, and by Tuesday, their mission was complete.

His team had explored various possibilities to get Machado out of the country, and settled on a plan that involved a tumultuous sea journey.

To protect his future work in Venezuela, Mr Stern can only reveal so much about the trip.

By land, they moved Machado from a house where she was in hiding, to a pick-up spot for a small boat, which took her off the coast to a slightly bigger boat where she met up with him.

The voyage was in “very rough seas” with waves of up to 10ft (3m) in “pitch-black darkness,” he said.

“The journey was not fun. It was cold, it was very wet, we were all soaked, the waves were very rough, and we used that to our advantage. We got her to land and to where her plane was, and she flew to Norway.”

Throughout the journey, he added that various steps were taken to mask and disguise Machado’s face, as well as her digital profile because she is so well-known.

“The biometric threat is so real,” he noted, adding steps were taken to make sure she could not be traced via her phone.

He said that Machado was “formidable” despite the conditions, accepting a jumper for warmth, but not asking for anything else.

“She was soaking wet and freezing cold and didn’t complain once,” he laughed, acknowledging the operation was very dangerous because water is “unforgiving”.

“If I am driving a boat and blow an engine, I’m swimming to Venezuela.”

When asked how he could guarantee the safety of Venezuelans who helped with the operation, Mr Stern said they kept their identities secret and “we [Grey Bull] do a lot of deception operations”.

Many of those who helped didn’t even realise they were working for him, Mr Stern said, while others think they “know the whole story”, but they really don’t.

“There are people who did things that were benign from their perspective – but mission-critical from our perspective.”

He said the operation was financed by donors, and not by the US government: “We’ve never had a thank-you note from the US government, let alone a dollar.”

Mr Stern said he did coordinate with some nation states, and with intelligence and diplomatic services of several countries. This included alerting the US in an “informal” manner.

Machado has said she intends to return to Venezuela, but Mr Stern said he advised her not to do that.

“I told her, ‘don’t go back. You’re a Mum. We need you.’ She’s going to do what she’s going to do… I understand why she wants to go back because she’s a hero to her people.

“I wish she wouldn’t go back; I have a feeling she will.”