Helmut Marko says that Max Verstappen's three-year contract with Red Bull Racing was a demand made directly by the Dutch driver.
Red Bull announced earlier today that it had secured Verstappen's services until the end of 2020, putting to rest speculation that the young prodigy could leave the Milton Keynes outfit at the end of next season.
"We started with Max in Formula 1, he had his first victory and now we want to achieve the championship title as the youngest F1 driver," Marko told Sky F1.
"Both drivers [Ricciardo and Verstappen]could have been free after 2018, so we tried to secure at least one driver, because Max asked if he could make a deal until 2020, while Ricciardo was putting himself on the market. And now we are talking with him."
Marko insisted on the fact that Verstappen's demand and subsequent deal underlined the driver's confidence in Red Bull Racing's ability to deliver a winning package.
"It shows how much he trusts us," Marko said.
On the subject of Toro Rosso, while the Faenza-based team has yet to determine its line-up for 2018, Marko explained that after bringing young drivers through the ranks, the priority was now to see the junior squad itself move up the grid, hence it's recently signed engine deal with Honda.
"Vettel, Ricciardo, Max, they all came from Toro Rosso, so we can say that the job we had to do is fulfilled," he said.
"But now he have the aim to bring the team itself further forward - not always finishing sixth.
"And I think a good step is now this engine deal and I'm sure whoever the drivers will be, they will do their job pretty well."
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