Twenty years since the Pentagon began taking bids from defense contractors, the F-35 fighter jet—the most expensive weapon ever made—is finally ready to see active duty over the Pacific Ocean. The U.S. Marine Corps expects to deploy 16 of the stealthy high-tech warplanes early next year at Iwakuni Air Station in Japan. From there, U.S. pilots will begin testing the jets in regular noncombat operations from the Navy’s USS Wasp amphibious assault vessel in what one commanding general has described as the “school of hard knocks.”