The U.S. Air Force has finally admitted that its new F-35 Joint Strike Fighter isn’t maneuverable enough to beat older jets in a dogfight. But despite its earlier promises that the pricey, radar-evading warplane would excel in close combat, now the flying branch insists that the stealthy F-35 doesn’t even need to dogfight.

At a conference in Maryland on September 15, General Herbert Carlisle, head of the Air Force’s Air Combat Command, described the F-35 as not as maneuverable as some of its predecessors.

“That’s not what the airplane was designed to do,” Carlisle added, according to National Defense magazine. “It’s a multi-role airplane that has an incredibly comprehensive, powerful, integrated avionics and sensor suite.”

Colonel Edward Sholtis, an Air Combat Command spokesman, said the F-35 would be able to compensate for its relative sluggishness. “The F-35 wasn’t optimized for dogfighting maneuvers, but that isn’t remotely close to saying it doesn’t bring its own advantages to the air superiority mission.”

Namely, the new fighter should be able to detect and shoot down enemy planes from long range, making close-in fights unnecessary. Plus, the Joint Strike Fighter will team up with F-22s, F/A-18s, F-15s, F-16s, and other U.S. dogfighters, each plane performing the particular mission it’s best at and helping make up for the other jets’ weaknesses.

“I’m unclear why it’s presumed I need to be on the defensive about the statement of an almost universal feature in the introduction of new aircraft into a combat fleet,” Sholtis told The Daily Beast. “Their strengths are exploited to best effect and their inevitable limitations are mitigated through tactical innovation, their integration with other aircraft with different attributes, technical upgrades, etc.”

The statement comes at a moment when China and a newly belligerent Russia are both making heavy investments in advanced dogfighters. And it contradicts what the Air Force and Lockheed Martin, the company working with the Pentagon to develop and build the F-35, used to say about the new fighter. The U.S. military is counting on the supersonic Joint Strike Fighter to replace almost all of its current frontline jets—including most F/A-18s and F-16s—at a cost of more than $400 billion. The Marine Corps declared the first F-35 squadron combat-ready in July. The Pentagon plans to buy as many as 2,400 of the planes.

In 2008, Air Force Major General Charles Davis, then in charge of the F-35’s development, told Reuters the single-engine stealth jet was four times more effective in air combat than older planes were. Around the same time, Lockheed described the Joint Strike Fighter as a “racehorse” with the most powerful engine ever installed in a fighter.

And in 2013, Lockheed test pilot Billy Flynn told Flight Global that in terms of maneuverability and acceleration, the F-35 was “comparable or better in every one of those metrics, sometimes by a significant margin,” than today’s leading fighters, including the European Typhoon and America’s own F/A-18 Super Hornet.

But by mid-2015, evidence was mounting that the heavy, complex Joint Strike Fighter—which the Pentagon expects to attack targets on the ground and in the air with equal aplomb—can’t turn or accelerate fast enough to win in a dogfight against current fighters, to say nothing of future fighters that might be even more maneuverable.

In late June, this reporter and his team at the blog War Is Boring obtained an internal U.S. government memo describing a trial dogfight between an F-35 test plane and an F-16, one of the older jets the F-35 is replacing in Air Force squadrons. “The F-35 was at a distinct energy disadvantage,” the F-35 test pilot wrote in a scathing, five-page brief after losing multiple mock dogfights against the F-16 pilot.

To close observers of the Joint Strike Fighter’s 20-year-long development, the dogfight report came as no surprise. The F-35’s variants were meant to replace about 90 percent of America’s tactical air fleet. That meant taking on a whole lot of jobs. In trying to do everything—fighting in the air, making bombing runs, launching from aircraft carriers and even taking off vertically from small assault ships while also avoiding enemy radars—the F-35 combines a lot of contradictory design elements.

It needs to fly slow for bombing missions but fast for aerial fighting, dictating a wing design that’s an unhappy compromise between straight and sleek.

It needs to haul lots of weapons for a wide range of missions but must also carry its munitions in an internal bomb bay in order to avoid creating a huge radar signature. That means a fat fuselage that’s big enough for a bomb bay, but which adds drag and slows down the plane.

Likewise, taking off vertically demands a downward-blasting second motor, but that motor is heavy and only adds to the F-35’s bulk.

And let’s not even get into the problems with the F-35’s sensor array, its weapons, or its susceptibility to being found by advanced radar.

Confronted with the growing awareness of the Joint Strike Fighter’s built-in limitations, this summer the Air Force and Lockheed began tweaking their public statements about the F-35.

In response to War Is Boring’s dogfight report, on July 1 the joint government-Lockheed program office overseeing the F-35 insisted the plane was never really meant for short-range aerial combat. “The F-35’s technology is designed to engage, shoot and kill its enemy from long distances, not necessarily in visual ‘dogfighting’ situations,” the program office stated on its website.

Besides, the office added, the F-35 in the dogfight test with the F-16 didn’t have all the high-tech equipment it would have had in frontline service, including a special helmet that should allow an F-35 pilot to fire a short-range air-to-air missile at an enemy plane from almost any angle by merely looking at the bad guy.

But with Carlisle’s September admission that the Joint Strike Fighter isn’t much of a dogfighter, the government’s subtle backpedaling from mid-summer has taken a nastier, more defensive tone.

“Your questions suggest you’ve resolved that these remarks somehow validate your settled opinion on the F-35, so I’m not sure how much this context matters to whatever you care to write,” Sholtis said when this reporter asked about Carlisle’s statement and the evolution of the Air Force’s position on the Joint Strike Fighter.

“I appreciate that you have strong opinions on the program, as many of us do, and that your rhetorical case is improved by treating nuance as waffling,” Sholtis added. “Unfortunately, the simplifications that work well in print don’t get you very far in the practical business of fielding a complex weapon system.”