F1 Red Bull boss rules out any Porsche takeover of the team
Media reports have suggested long-standing talks between the two parties are stalling due to a gap between how much control the Volkswagen-owned marque wanted and what Red Bull was prepared to give.
Horner told Sky Sports television ahead of the Dutch Grand Prix that there was not much to report but "any relationship with any manufacturer or partner would have to fit with Red Bull.
"Red Bull has always been an independent team. It's been one of our strengths, it’s been the backbone of what we've achieved and our ability to move quickly," he added.
"It's part of the DNA of who we are that we're not a corporately-operated organization. That is one of our strengths in how we operate as a race team and that is an absolute pre-requisite for the future.
"They (Porsche) need to decide whether they want to join that party or not but it would have to be within the culture of the way that we go racing."
Volkswagen-owned Audi announced last week it will build an engine in Germany and enter in 2026 with an existing team, likely to be Sauber, and the sport has been waiting for Porsche's move.
Championship leaders Red Bull have set up their own powertrain company, recruiting from rivals Mercedes and others, based in Milton Keynes.
The first Red Bull engine fired up shortly before the sport's August break and Horner made clear the team were ready to go it alone.
"We’re in good shape and time will tell whether we embrace a partner into that programme or as the plan is at present to continue on our own," he said.
Red Bull have a power unit support agreement with former partners Honda until the end of 2025 but there has been speculation also that the Japanese manufacturer might seek a return in 2026.
"Honda obviously withdrew from Formula One, they’ve kept a toe in with the agreement we have... they are making noises about 2026 but our train has left the station," said Horner.
"We’ve committed to the investment within Red Bull Powertrains. We’re circa 300 people now working on that 2026 engine so any agreement with any potential partner or OEM would need to fit with that."