Toro Rosso has confirmed it will use Honda Formula 1 engines from next year in place of Renault after agreeing a "multi-year" deal.
Although the length of the deal was not formally announced beyond a "multi-year" arrangement, Autosport reported on Thursday an agreement is in place for three years.
Toro Rosso director James Key explained that work is under way to adapt the team's 2018 car to take Honda engines, but that this will not require drastic changes despite the late deal.
"It will be a question of adaption of our plans rather than a wholesale change and we are in the process of replanning our design and production activities in conjunction with Honda to ensure that we both hit all our important deadlines," said Key.
"There are some challenges to face given the time of year but Toro Rosso has faced many difficult tasks with timing in the past and has the flexibility to deal with it.
"We will be working hard not to only redesign the power unit installation but also ensure that this has minimal or no effect on the ongoing development work for 2018 - that is our current target.
"The architecture of the car will change in line with the power unit requirements and our chassis and gearbox designs are currently under review to be adapted accordingly.
"Similarly we will be working closely with Honda on the performance aspects of the power unit installation that the chassis will influence to ensure we maximise the potential of the package as a whole from the outset.
"We look forward to a strong, stable and proactive partnership with our colleagues at Honda."
Takahiro Hachigo, president of Honda Motor Company, thanked the FIA and commercial rights holder Liberty Media for the part it played in the deal happening.
"Toro Rosso is an experienced team with a youthful energy and history of nurturing the stars of the future," said Hachigo.
"Everyone at Honda is looking forward to working with Toro Rosso, and we are excited to start this new chapter in our Formula 1 journey with them.
"I would like to express our appreciation to Liberty Media and the FIA for their cooperation toward the realisation of this partnership.
"Honda and Toro Rosso will work as one team to strive for progress and a successful future together.
"We appreciate the support of our fans as we begin this challenge."
Toro Rosso has yet to confirm its 2018 driver line-up, although Honda protege Nobuharu Matsushita is a candidate should he secure enough superlicence points by finishing in the top three in the Formula 2 standings this year, in which he is currently sixth.
A Renault statement said that the termination of its supply deal with Toro Rosso, which started in 2014, was "mutually agreed".
It is understood McLaren has not been asked to supply Toro Rosso with a gearbox as part of the deal.