Honda's previous management decided not to renew its Red Bull deal that expired at the end of 2021, right when Red Bull and Honda were starting to harvest the fruits of their partnership.
Honda did not pull out for financial reasons but cited a shift of focus to developing alternative energy forms with a view to becoming carbon neutral by 2050.
It was the latest indictment of F1's current power unit regulations which put heavy emphasis on the innovative MGU-H system, which uses exhaust gas heat to generate energy and reduce turbo lag.
The MGU-H plays a large part in the unprecedented thermal efficiency of the current crop of F1 cars, but its detractors argued it also bore little road relevance as it proved a stumbling block for many OEMs to enter the series.
But the 2026 engine regulations will do away with the complicated system and put more emphasis on energy harvested under braking by the MGU-K, which led to several manufacturers giving F1 another look.
Audi decided to join forces with Sauber, which currently runs under the Alfa Romeo moniker, and Red Bull secured Ford as its 2026 works backer.
With Red Bull off the table, Honda Racing Corporation landed on Aston Martin to make a swift return as a fully-fledged power unit manufacturer, while it is still supporting Red Bull with its current power unit.
Honda believes the new engine formula with its larger percentage of electrification and a move towards carbon neutrality has made F1 compatible again with the Japanese giant's mass EV plans.
"The biggest key factor for this decision this time around was the direction that the new 2026 regulations are facing towards, which is moving towards carbon neutrality," said HRC president Koji Watanabe.
"And that direction or that was matched with our company's goal moving into the future. That is the decisive key factor.
"Currently, the electrical power accounts for 20% or less as opposed to the internal combustion engine, but the new regulations would require about 50% or more of electrification, which would move even further towards electrification.
Honda CEO Toshihiro Mibe added: "With the new 2026 regulations, the key for winning will be a compact, lightweight, and high-power electric motor with a high-performance battery capable of handling high and swift power output, as well as the energy management technology.
"We believe that the technologies and know-how gained from this new challenge can potentially be applied directly to our future mass production electric vehicles, such as an electric flagship sports model, and electrification technologies in various areas, including eVTOL which is currently under research and development."
In 2026 F1 will also move towards the use of 100% renewable biofuel, which Watanabe said was a match for Honda's strategy.
"The 2026 regulations would obligate us to go 100% towards carbon-neutral fuel and that would require us to really think about how to integrate the new fuel with the internal combustion engine," he explained.
"We also would have to think about how to make the efficiency optimised in order to speed up and I think that direction matches with Honda's direction."
Honda recently announced its target to double its global EV and hydrogen sales by 2024 and is planning to produce more than two million EVs annually by 2030.
