Helmut Marko says that Renault's inferior budget put the manufacturer's engine behind its Mercedes and Ferrari rivals, leaving Red Bull no other choice but to split with its long-time partner.
While the Red Bull-Renault relationship had been a successful one in the past, with four consecutive world titles won between 2010 and 2013, the association lost its lustre thereafter, eventually dissolving in the past couple of years on the back of simmering conflicts.
According to Marko, Red Bull was left with no other choice but to switch its allegiance to Honda from 2019.
"For us, it was clear at one point that Renault could not deliver us a victorious engine," Marko told Motorsport-Magazin.
"With their budget, you cannot expect them to fight against Ferrari and Mercedes. It was clear that we had to do something.
"Now for the first time in our history, we have a factory engine [Honda]. There is a good development, and all that has happened so far is good for Red Bull Racing and Toro Rosso for next season."
The jury is still out as to whether Honda will provide the performance and reliability that Red Bull so desperately needs. A doubt compounded by the many grid penalties endured by Toro Rosso's drivers this season.
Marko however is convinced Red Bull has made the right decision for its future, with all due respect to Renault Sport F1 boss Cyril Abiteboul.
"The Honda engine has been improved generally, many penalties have been taken into account because we have always wanted to bring something new," added the Austrian.
"According to our simulations, we would have a much better appearance with the current Honda engine. But we do not need to think about that, Mr Abiteboul, and next year we will see."
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