Red Bull team principal Christian Horner says that the decision to switch from Renault to Honda power for the 2019 Formula 1 season was a "pretty clear cut" technical choice.
Its sister team Toro Rosso moved to Honda engines this year, allowing Red Bull to monitor the Japanese manufacturer's progress - including the update it introduced for the Canadian Grand Prix earlier this month.
"We've been in a privileged position to have a front row seat to monitor the progress of how Honda have been getting on in our sister team at Toro Rosso versus our own power supply," Horner said in a video issued by Red Bull.
"It's been great to see that progress. We've come to the conclusion that Honda are making good strides, good progress on both performance and reliability, and therefore we've made the difficult decision to change power units after 12 seasons to something new for 2019 onwards.
"We've had the privilege of seeing how they've progressed this year, and reached the conclusion that purely for technically driven reasons that this is the right move for Aston Martin Red Bull Racing."
Red Bull had long insisted it would announce its engine plans around the Austrian GP next week, but Horner admitted the decision was brought forward because it felt it had all the data it needed and amid pressure from Renault.
"Based on the information we had from Montreal, our decision, driven by engineering, was pretty clear cut in the end," he said.
"Rather than things getting delayed, or taking further time, and Renault were also very interested to have a decision as soon as possible to get their own plans in place, we decided that the timing was right to make that commitment, make that decision, and hence the announcement today."
Horner made it clear that he expects Red Bull to be in a winning position with Honda.
"Our determination as a team is to keep closing the gap to our immediate competitors," he said.
"We've been trying to do that over the last couple of years, and of course the power unit is a vital element within an F1 car, and we're confident that Honda have the right infrastructure, the right resources, the right technical capacity and determination to help us in our quest to reduce the gap to the teams ahead of us, Ferrari and Mercedes."
He insisted that Red Bull not given up on achieving further success with Renault before the end of this season.
"We're very much focused on the 2018 world championship, we have an outside chance in both championships, we've won two grands prix so far this year, we're third in the constructors' championship, and there's a long way to go," said Horner.
"So we're going to be pushing all the way to the finish, and we're going to be relying on support from Renault to the end of the year, which I'm sure they will give unwaveringly, as they have done during our previous 11 seasons."