Honda sources have confirmed to AUTOSPORT that it plans to return to Formula 1 as an engine supplier to McLaren.
But while the new turbocharged 1.6-litre V6 powerplants will be introduced next season, a McLaren-Honda isn't expected to be on the grid until 2015.
McLaren currently has the option to run Mercedes engines until the end of 2015 as part of the deal in which it bought back the 40 per cent stake that the German manufacturer owned of the team, which was completed in 2011.
This means that McLaren is free to make a switch to Honda, which it is set to do in 2015.
When asked by AUTOSPORT whether he could confirm that the team would run Mercedes engines in 2014 and 2015, Whitmarsh said: "I can definitely say that we are with them for some time, we have a contract and we have been talking about it for some time.
"There is nothing to announce at the moment. I can't elaborate any further.
"We have a contract that covers the next three seasons at the moment and we will certainly go into next year with Mercedes-Benz.
"We have a long and successful partnership with them."
Whitmarsh added that talk about new engine suppliers coming into F1 can only be good for the sport.
Three engine manufacturers - Ferrari, Mercedes and Renault - must supply all 11 teams in 2014, but from 2015, Honda is set to make it four.
"We have read the stories about Porsche, Hyundai and Honda and I think they are to be encouraged," said Whitmarsh.
"The sport needs new automotive manufacturers to come in and if we can help that in any way, we will do so, but at the moment we are very focused on our partnership [with Mercedes], which has been a very good partnership.
"We are going to try and win championships with them in the future."
F1 editor Edd Straw
Sometimes quotes, in the cold light of day, don't tell the whole story. But there can be no doubt about the meaning of Martin Whitmarsh's very deliberate answer when asked to confirm whether McLaren would use Mercedes power in 2014 and 2015.
For the record, our question was as follows: "You said the other day to Sky that you have got a contract [with Mercedes] for 2014 and 2015, which is well known. What I would like to know is do you plan to pick up the option for first 2014 and secondly 2015 with Mercedes? Can you categorically say that you will run their engines for the two seasons that follow this one?"
That he specifically confirmed next season, but dodged the issue of 2015 is telling.
While the dotting of the i's and the crossing of the t's might be incomplete, both McLaren and Honda plan to renew their partnership on track in 2015.
Given the success last time around - five seasons from 1988-1992 that yielded four drivers/constructors' championship doubles - that can only be good news for McLaren.
Not to mention cause for concern among its rivals...