 When near to the ground, the Boeing X-32 suffered from the problem of hot air from the exhaust circulating back to the main engine, which caused the thrust to weaken and the engine to overheat.The United States Department of Defense officials and William Bach, the UK Minister of Defence Procurement, said the X-35 consistently outperformed the X-32, although both met or exceeded requirements.The development of the JSF was jointly funded by the United States, United Kingdom, Italy, the Netherlands, Canada, Turkey, Australia, Norway and Denmark.