Red Bull believes it will be treading water in F1 in 2016

The team's 2015 F1 campaign was dominated by rows over its engine supply, as it tried to jettison long-time partner Renault for Mercedes, and then turned to Ferrari and Honda in vain when that plan fell through, with its future in the championship in doubt throughout that period.

Red Bull eventually ended up back with Renault in a restructured deal involving reduced support and the engines being badged by TAG Heuer.

Horner - a vociferous critic of Renault this year - doubts there will be an imminent engine performance upturn early in 2016.

"[2015 was] a different challenge and we haven't lost any major team members," he said.

"The team have done a tremendous job of getting their head down and focusing on the chassis.

"And the chassis was developed and developed through the year, and I believe we've got a very strong chassis.

"We're just going to have to tread water for a moment until we get ourselves back onto the front foot and our time will come again."

He believes the Red Bull team grew stronger through its "year in adversity" in 2015.

"Sometimes it brings a group closer together and I feel the team is tighter and closer than it's ever been," said Horner.

"So actually I don't, from a team perspective, think it was a bad year.

"We've been very strong on strategy, our pitstops have been the best in the pitlane.

"We've outdeveloped others chassis-wise, we've had a tremendous car.

"We've grabbed the three opportunities that might be available to us in Monaco, Hungary and Singapore.

"Two out of the three, we got on the second step of the podium.

"As a team, when you actually drill down and look into how we performed, we've actually done a very strong job.

"Certain things, which are beyond our responsibility, we can't control.

"You can only worry about the things that you can control."