Red Bull Team Principal Christian Horner has questioned whether Aston Martin will gain an advantage by switching to Honda power units in 2026.
The Silverstone-based outfit will become the Honda works outfit when new power unit regulations are ushered into F1, with the Japanese manufacturer confirmed as the sixth OEM to take to the grid.
Aston Martin started the year as Red Bull's closest challenger before being overtaken by Mercedes after the Brackley-based outfit secured a double podium finish at the Spanish Grand Prix.
Asked if he still saw Aston Martin as the team's nearest competitor, Horner told media, including RacingNews365.com: "They're putting a good team together.
"Honda, it is good to see them continuing in the sport. They have obviously done a significant U-turn from where they were circa 18 months, two years ago.
"But I think that their decision, in many ways, forced us to make a decision about our long-term future, not being beholden upon a manufacturer and taking control of our own future.
"By making that investment that we have in Red Bull Powertrains, it has enabled us to put the whole thing under one roof.
"It is a huge task for 2026, but one that we are really excited about. For the long-term prospects of the team and its longevity and competitiveness of having engine engineers and chassis engineers sitting under the same roof for a fully integrated drivetrain, that will pay dividends in the long run."
Viewed by others:
Aston Martin independence
"They [Aston Martin] will get a competitive engine, but they already have a competitive engine," added Horner, pointing to the existing partnership between Aston Martin and Mercedes.
"They will perhaps achieve more independence through, I guess, their architecture is currently dictated by another team.
"And it is very expensive for them in the cap. The transferable components come with a big tax on them.
"So it's not cost-efficient for them to be a customer."