Ever since news first broke that the Air Force was being pressured by Pentagon officials to procure new F-15 airframes in 2020, pundits, lawmakers and defense officials alike have protested in the name of America’s most advanced fighter platform, the F-35. Now, with the Air Force’s F-35 order looking like it will be short of projections, some are sure to cry foul.

The F-35 is objectively a more capable multi-function platform than the air superiority-specific F-15X, thanks to its advanced sensor suite and stealth design. Still, the branch’s need to maintain fourth-generation platforms throughout the 2030s has made Boeing’s F-15X a promising solution to the problems presented by America’s long-in-the-tooth fleets of F-15s. The Department of Defense (DoD), Air Force, and even Lockheed Martin officials have repeatedly stated that F-15X purchases will not have any effect on F-35 procurement, but according to reports, the 2020 budget will only request 78 new F-35s. That’s six fewer than previously planned.

With a dozen new F-15X’s said to be included in the same budget request, it seems likely the drop in F-35 orders will ruffle some feathers. However, according to Pat Shanahan, acting Defense Secretary (and notably, a former Boeing executive), the drop in F-35s has nothing to do with the new (old) jets, but rather with continuing concerns regarding how incredibly expensive the F-35 is to operate.

“What’s really important for people to always take away is I’ve found the aircraft — the F-35 as a product, its capability and performance — to be eye-watering. It is high, high-performing — no ambiguity — no ifs, ands or buts,” Shanahan said, seemingly attempting to assuage previous claims that he’s been overly critical of the platform.

“This is the largest program in DoD history and the cost of sustainment is about the same cost as nuclear modernization,” Shanahan continued. He pointed out the F-35 is just entering into what is expected to be decades of service life, adding, if there was ever a time to “fix” concerns about operational costs and “if you were ever going to realize high performance — you would do it on the front end. We have a small window.”

Those remarks run counter to the F-35 talking points that have been pervasive throughout Air Force press interactions recently. Just about every conversation you have with an Air Force official about the F-35 has included some mention of the term “quarterback.” That refers to the aircraft’s ability to fuse data and relay it to less advanced platforms. It’s also noted the F-35 requires less subsidiary support than older platforms tend to need for maintenance. In effect, the argument is that F-35 maintenance costs seem high, but there are savings to be found outside the parameters of normal cost estimates.

Last year, the Air Force sang a very different tune, when it threatened to reduce its overall order of F-35s unless operating costs could be whittled down to a manageable level. According to the Air Force, that manageable level would need to be a whopping 38% lower than maintenance is expected to cost. Recent projections show the F-35’s maintenance alone will run the United States somewhere in the neighborhood of $1.1 trillion over the course of the jet’s service life. As a result, the Air Force would be on the hook for around $3.8 billion per year in maintenance costs.

“Right now, we can’t afford the sustainment costs we have on the F-35, and we’re committed to changing that,” Under Secretary of Defense for Acquisition and Sustainment Ellen Lord said last year.

Secretary Shanahan also pointed out that those exorbitant costs aren’t entirely on Lockheed Martin, though they are contracted for the aircraft’s maintenance and support.

“People write about it like it’s just Lockheed,” Shanahan said. “It’s Lockheed, it’s BAE, it’s Northrop. There’s a lot of opportunity to achieve higher levels of performance. There’s a big opportunity.”