The Pentagon wants to make it so by 2025. What You Should Know: The F-35 is the world's most expensive defense program ever. With time and experience can some of the costs come down? In addition to being one of the most expensive military hardware platforms ever developed, the Lockheed Martin F-35 Lightning II Joint Strike Fighter is also extremely expensive to operate. A year ago it was estimated that the fifth-generation advanced stealth aircraft cost around $44,000 an hour to fly—or put another way $44 million to fly 1,000 hours. That could be $352 million over the 8,000-hour lifespan of the jet, which is more than twice as much as every other fighter aircraft in the U.S. military’s arsenal.