Honda will quit Formula One at the end of next season, leaving Red Bull without an engine supplier.
Honda had walked away from the sport on the eve of the 2009 season as a manufacturer but returned as McLaren’s engine supplier for the 2015 campaign.
After severing ties with the British team, it has been working with Red Bull since the beginning of last year.
Honda said its decision had come because of a push for “future power unit and energy technologies” in its road cars.
Red Bull team principal Christian Horner said: “Their decision presents obvious challenges for us, but we are equipped to respond effectively.”
