Ferrari did not supply Red Bull with its Formula 1 engine for 2016 because it would have been "dangerous" to the Scuderia's competitiveness, says its president Sergio Marchionne.
Red Bull was in need of a power unit supplier after initially trying to terminate its deal with Renault, and a deal it believed it had with Mercedes for 2016 fell through.
Ferrari considered the partnership before opting against it, and Red Bull also had a Honda tie-up vetoed by McLaren before eventually agreeing a deal with Renault to continue using its engine with TAG Heuer branding.
When asked to explain the reasoning behind Ferrari's decision, Marchionne said his priority was ensuring its works team was in the best possible position to win and supplying Red Bull would have risked that.
"We had to cope with some uncertainties of our own architecture and we had to bridge the technological gap," said Marchionne.
"So committing to providing an equivalent power unit to a team that has a chassis design technical ability to compete could have been dangerous to Ferrari's competitiveness.
"My main commitment is to support and protect Ferrari. I'm not interested in defeating Mercedes with Red Bull.
"If someone says let's use Ferrari's engine so we can defeat Mercedes, I'm not interested in that argument. I want Ferrari to win.
"We know Red Bull's abilities are good, they destroyed us with Sebastian Vettel and the championships they won."
Ferrari currently supplies Sauber and Manor, and Marchionne claimed in June the company would have been "glad" to supply Red Bull as well.
But the Italian said it would not make sense for Ferrari to spend hundreds of millions developing an engine only to give it Red Bull for a fraction of the cost and then be beaten.
"If we look at Red Bull investing important amounts into their chassis development and then we equip them with a power unit at a certain price reflecting much higher investment than what they pay for, it's inequality on the track," he said.
"We're not interested in that."
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