Red Bull boss Christian Horner says his team is now in a 'critical' situation over its engine plans, amid uncertainty that Ferrari will give the team what it wants.
Although the energy drinks giant made clear last week that its F1 future rested on it getting a deal that guarantees performance parity with Ferrari, it is understood that such a request has fallen on deaf ears.
Horner appeared in a downbeat mood after the Japanese GP, as talks with Ferrari appear not to be delivering what he had hoped for.
"The current situation is quite critical because, as we sit here, we don't have an engine," said Horner.
"We are already late, already very late. For Toro Rosso it is more critical than Red Bull. It was already difficult two weeks ago."
One potential avenue could be in it threatening to hold out and block a push by manufacturers to allow in-season engine development next year if it cannot get an up-to-date power unit.
If Red Bull fails in all its attempts to get the engine it wants, then a withdrawal after Abu Dhabi is on the cards.
Horner added: "The important thing for us is to have a first class engine. First of all we need to conclude our situation with our current supplier, but I think Dietrich Mateschitz has made the situation very clear."
"We don't offer any engines," he said. "When people are talking about business they do not share what they are doing with all the press, and I am not doing so."
Horner has suggested that if Mateschitz does decide to shut his teams down, then the focus will switch to finding other activities for the staff.
"If we are in a position where we cannot compete, then for sure we will have to look at other activities," he said.
"Milton Keynes is full of a lot of talent and we have to look at where we apply that talent."