WASHINGTON — The U.S. Air Force should abandon its plans to revive fourth-generation fighters under the F-15EX program, and instead focus on building more F-35As and new stealthy fighter jets, according to a new paper from the Mitchell Institute for Aerospace Studies.

Former F-16 pilot Heather Penney, a senior resident fellow at the institute, said in the paper released Monday that the F-15EX Eagle II program is a dead end — one based on outdated technology that wouldn’t suit the Air Force well in a high-end fight nor save money over the F-35 program. She expects the stealth-less F-15EX will end up playing a limited defensive role in a war, at a time when the Air Force has a limited inventory of fighters.

“Given this reality, funding limitations and modern mission demands, the Air Force should seek the soonest reasonable termination point for the F-15EX,” Penney wrote.

The Air Force should instead shift that money to boosting F-35 production and develop another fighter jet, Penney said — one that is affordable, flexible and has stealth capability. This would be in addition to the highly classified Next Generation Air Dominance program that would start fielding sometime in the 2030s, to which Penney said the Air Force should commit wholeheartedly.

In underscoring the importance of fielding stealthy fighters, Penney pointed to the Air Force’s recent experience in Syria. The country possessed Russian-made S-400 surface-to-air missile systems, which the U.S. Air Force could only counter by deploying F-22s and F-35s, she said.

And other potential foes, such as China, Russia and Iran, will undoubtedly field that air defense system or something similar, requiring the American service to fight with something more capable than a fourth-generation fighter.

“Any modern battlespace will require advanced stealth capabilities, just as the cost of entry,” Penney said.

And if the Air Force allows a capability gap in its fighter force, Penny said, that could give China the opening it seeks to quickly and decisively seize Taiwan.

The Mitchell Institute counts several defense contractors among its financial backers, including Boeing, which makes the F-15EX, and Lockheed Martin, which makes the F-35. The institute said this report was paid for out of its general funds, and not bankrolled by particular contractors.

In addition to pulling the plug on the F-15EX, Penney said the Air Force should completely divest its other F-15s — the “C,” “D,” and “E” models — as well as the A-10 Warthog from its fleet. Those retirements should happen on a one-to-one basis as F-35s come online, she added.

She also called on the service to extend its legacy F-16s to provide air power in permissive environments, as well as retaining and continuing to modernize the F-22 Raptor until the Next Generation Air Dominance and other programs are battle-capable. Little is publicly known about the Air Force’s secretive and experimental NGAD program, although the service confirmed last year that it quickly designed, built and flew a prototype — years ahead of schedule.

When asked what she wanted to see from NGAD, Penney responded: “Range and payload.”

The Air Force will need a future fighter that can penetrate deep into enemy territory, with enough firepower to destroy mobile or difficult targets, she explained. Trying to hit targets from a distance won’t cut it, she added.

“It does not make sense to build a standoff force” that would strike targets from a distance, Penney said. “It’s simply too expensive. It’s not operationally effective. You must have penetration and ... be a stand-in force whenever you execute … prolonged combat operations.”

Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at Military.com. He has traveled to the Middle East to cover U.S. Air Force operations.

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