The design of the "sixth-generation" aircraft remains a closely-guarded secret, but reportedly includes high advanced sensors and engines in addition to their stealth capabilities. An artistic rendering alongside Trump in the Oval Office of the White House only showed a small part of the aircraft and front landing gear. "There's never been anything even close to it, from speed to maneuverability, to what it can have, to payload," Trump said. Trump said the US military selected the number 47 - which he described as a "beautiful number" - for the aircraft. He is the 45th and 47th President of the US. "The generals picked that title," he said. The Boeing deal also marks a defeat for competitor Lockheed Martin, which was recently eliminated from a separate competition to build a next-generation aircraft for the US Navy. Sales of the company's F-35 Joint Strike Fighter, a fifth-generation aircraft, could also be threatened by mounting trade tensions between the US and its allies abroad. Canada's new prime minister, Mark Carney, has asked defence minister Bill Blair to review its purchase of the aircraft, which was developed with Canada as a partnership. In Portugal, the country's outgoing defence minister told local media that the country is re-thinking a purchase of F-35s to replace its older aircraft as a result of "recent positions" taken by the US government. Each F-35 costs approximately $85m (£65.8m), with the price rising up to $150m with spare parts and support infrastructure included. About 1,100 of the aircraft have been built, with F-35s in service with 16 militaries around the world. Several countries are reportedly now mulling purchasing aircraft from European manufacturers such as Dassault and Saab, even if those aircraft lack the stealth capabilities of the F-35. Elon Musk, a key ally of Trump's, has previously expressed scepticism of manned aircraft. He was at the Pentagon ahead of the F-47 announcement on Friday, on a visit which defence secretary Pete Hegseth said was related to cost-cutting.