President Joe Biden’s new defense budget reveals a startling change of course from what the Air Force has previously said it needs. For fiscal year 2023, the service has requested the purchase of just 33 F-35s, 15 less than in FY22—so it can purchase more F-15EXs.

The administration argues that the latter is less expensive to buy and to fly than the fifth generation F-35A. But looking at publicly available documents, it appears both arguments are patently false.

Let’s start with the sticker price. The Air Force Financial Management website presents cost data for the F-35A and the F-15EX that allows us to compare pricing for each fighter, line-by-line.

There we find that the FY22 “flyaway cost” for an F-35A is $85.8 million. That buys a $53.4 million stealth airframe, a $12.8 million engine, internal targeting and Infrared search and track (IRST) systems, and a $12.2 million offensive and defensive electronics package. That is a complete package—all the equipment pilots need to detect, geolocate and engage targets electronically or kinetically in even the highest threat environments.

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The price the Defense Department errantly quotes for the flyaway cost of the F-15EX is $97.9 million. Correcting a math error in that document renders a cost of 89.8 million that includes a $73.2 million non-stealth airframe, two engines totaling $11.31 million, $1.2 million in Auxiliary Mission Equipment, $1.1 million in software engineering.

Mysteriously, the cost for the jet’s $13.6 million offensive and defensive electronics package, known as the Eagle Passive Active Warning and Survivability System or “EPAWSS” is not included in the jet’s flyaway costs. Nor can you find the jet’s $2.5 million targeting and $10.9 million IRST pods the jet will need to match the basic combat capability of the F-35A.

It turns out the pricing senior leaders have been given to justify the purchase of the F-15EX is not actually for the F-15EX—just a spiffier airshow version of the F-15E without the systems it needs to fly combat missions in low or permissive threat environments.

Adding those systems in to what the $89.8 million the website speciously tallies as the F-15EX flyaway cost brings its real flyaway cost to $117 million—$31.2 million more than a fully combat-capable, F-35A stealth fighter.

But the cost discrepancies only get more pronounced.

The “Gross Weapons Systems” cost includes the “flyaway cost” and the per-jet share of the cost of unique equipment, simulators, and standing-up depots needed to support the aircraft. The gross weapons system cost of an F-35A adds up to $98.2 million in FY22.

The defense department calculates the F-15EX at $110 million. But that does NOT include the cost for simulators, EPAWSS, or the targeting and IRST pods required for combat. Adding in those costs brings the gross weapons systems cost for the F-15EX to $136.7 million—$38.5 million or 39 percent more than a fully loaded F-35A.

So, the savings must be in the cost to operate each system, right?

Senior leaders and the Defense Department’s office of Cost Assessment and Program Evaluation (CAPE) have long derided the F-35A as having excessive operational costs, well above those of the F-15EX.

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Yet, an internal, unclassified CAPE chart Breaking Defense has reviewed tells a very different tale. It shows the cost to fly an F-15E for a full year is $7.7 million, compared to only $7 million for an F-35A. With the additional requirement to maintain EPAWSS and the IRST pod, the F-15EX will very likely cost more.

How could the Defense Department make such a glaring mistake on the acquisition cost of the F-15EX? And why, after its own cost estimates show the F-35A is 10 percent cheaper to operate than the F-15E, would CAPE intentionally keep those details to themselves?

Certainly the Pentagon has some explaining to do, but the important thing now is to get this right.

In the wake of Putin’s invasion of Ukraine and a rising China, we need to field the best fighter anywhere in numbers that matter, and we need to do it now. The F-35A is much cheaper to buy and fly than the F-15EX—and if you are wondering which jet Air Force pilots prefer, just ask them. I did, and those who transitioned from the F-15E to F-35A—or any other fourth generation fighter—would never go back. Neither should we.