Red Bull have begun official communication with engine manufacturer Honda ahead of becoming partners for the 2019 season and beyond.
After Honda's divorce from McLaren last season, the Japanese suppliers joined forces with Toro Rosso and are off to a much more reliable start than first anticipated.
Red Bull are currently in partnership with Renault, but their relationship is not the healthiest given the continued reliability concerns and their existing deal expires at the end of the season.
As a result, Red Bull are now fully exploring the idea of whether to take on Honda power units as early as next season.
Masashi Yamamoto, director of Honda Motorsport; and Helmut Marko, advisor for Red Bull Racing, met at the Azerbaijan Grand Prix to discuss their current positions and talks are understood to have gone well.
Yamamoto said: "We formally sat down for the first time, and started talking about specific requirements for the deal to move forward.
"Red Bull is a competitive team, and Honda would be open to supply them if there is an opportunity.
"We have moved on from casual discussions to formal negotiations, and we confirmed our points of view and are now at the start of the process."
Teams have until May 15 to confirm to the FIA which engine they intend on using for the following season.