With a sticker price of around $100 million per plane, including the engine, the F-35 is expensive. While stealthy and brimming with high-tech sensors, it’s also maintenance-intensive, buggy and unreliable. “The F-35 is not a low-cost, lightweight fighter,” said Dan Ward, a former Air Force program manager and the author of popular business books including The Simplicity Cycle.

The F-35 is a Ferrari, Brown told reporters last Wednesday. “You don’t drive your Ferrari to work every day, you only drive it on Sundays. This is our ‘high end’ [fighter], we want to make sure we don’t use it all for the low-end fight.”

“I want to moderate how much we’re using those aircraft,” Brown said.

Hence the need for a new low-end fighter to pick up the slack in day-to-day operations. Today, the Air Force’s roughly 1,000 F-16s meet that need. But the flying branch hasn’t bought a new F-16 from Lockheed since 2001. The F-16s are old.