LONDON (Reuters) - Red Bull respect engine supplier Honda’s decision to leave Formula One at the end of 2021 and are well equipped to deal with the ‘obvious challenges’ presented by the departure, team boss Christian Horner said on Friday. Honda said in a statement it wanted to focus its research and development resources on energy technologies including for fuel cells and battery electric vehicles. The Japanese carmaker supplies two Red Bull owned F1 teams -- Red Bull Racing and Italy-based AlphaTauri (previously Toro Rosso). Both teams have been grand prix winners this season, making Honda the only engine supplier to have won with two different teams in the V6 turbo hybrid era that started in 2014 and that has been dominated by Mercedes. “The shifting focus within the automotive industry has led to Honda’s decision to re-deploy their resources and we understand and respect the reasoning behind this,” said Horner in a statement. “Their decision presents obvious challenges for us as a Team but we have been here before and with our strength in depth we are well prepared and equipped to respond effectively, as we have proven in the past.” Honda’s departure will leave only Mercedes, Ferrari and Renault as Formula One engine makers. Horner said Red Bull, whose main driver is highly-rated Dutch 23-year-old Max Verstappen, would evaluate their options as a group. Red Bull won four constructors’ titles in a row with Renault from 2010-13 but the relationship with the French manufacturer soured in the V6 era, with the team branding the engines as Tag Heuer for a period. Both Red Bull-owned teams have used Ferrari units previously, but the Italian manufacturer’s power unit has lost performance this season. Mercedes already supply Racing Point and Williams as well as their own factory team and are due to provide engines to McLaren, currently with Renault, next year. “Whilst we are disappointed not to continue our partnership with Honda, we are enormously proud of our joint success, delivering five wins and 15 podiums for both Red Bull owned teams,” said Horner. He said Red Bull remained committed to the sport in the long term, having recently signed a new commercial agreement for the next five years.