As Red Bull’s options narrow further, Ferrari boss Maurizio Arrivabene has played down the prospect of a 2016 engine deal.
And the Italian told Brazil’s Globo that the perception that the fate of Red Bull and Toro Rosso and hundreds of employees is now in the hands of Ferrari is wrong.
"Red Bull has no engine for 2016 and it seems that we are guilty, but it’s not like that," Arrivabene insisted.
It is believed that Ferrari has told Red Bull that the only workable solution for 2016 is that the two teams accept a supply of year-old power units — something Dietrich Mateschitz says is unacceptable.
But Arrivabene said time is simply too short for Ferrari to cope with producing enough 2016 engines to supply the works team, Haas, Sauber and two additional teams.
"We have to plan everything we do, obviously," he said. "And our review of the new power unit development programme and the production, to satisfy another team, would require us to change everything we have planned so far."
So if Red Bull has painted itself into a corner, that was their own doing, Arrivabene argues.
"I am convinced that they were certain they would use the Mercedes engine in 2016," he said. "So much so that they not only reviewed (cancelled) the contract with Renault but also with Infiniti and Total."
But Mercedes said categorically no, and "Only then did they come looking for us", Arrivabene said.
"If they had done so in June, for example, there would still be time for us to look at it. But to come talking to us after Monza...
"To think about a fourth team now, we need engineers who are trained by us to monitor the use of these engines, as we do with Sauber and Manor today," he said.
"And these guys cannot be young people who are just leaving university. F1 is not like that.
"If tomorrow the president of our company (Sergio Marchionne) called me and said ’Give the engines to them’, we would have to change everything that we planned very carefully long ago," said Arrivabene.