The F-35 Joint Strike Fighter, the $400 billion futuristic jet program that so many love to hate, found itself, once again, in the crosshairs this week when a popular military blog published  a report from a test pilot who apparently found its performance less than stellar.

“Test pilot admits the F-35 can’t dogfight,” read the headline in War is Boring. “New stealth fighter is dead meat in air battle.”

By now, after years of media beating up the most expensive weapons program in the history of the U.S. military, the Pentagon’s joint program office and Lockheed Martin, the prime contractor, have well-oiled media response teams that are quick to rush to the plane’s defense. And they wasted no time as the War is Boring report gained traction in military circles.

In an e-mail to reporters Wednesday morning, they said the report “did not tell the entire story” of the test dogfight between an F-35 and an F-16 this year because the F-35 was not equipped with many of the features that gives it an advantage. But they did not dispute the authenticity of the pilot’s remarks, and said they were investigating how the report, marked “For Official Use Only,” was leaked.

For years, the F-35 has been held up as the embodiment of government waste, a program years behind schedule and billions of dollars over budget. Sen. John McCain (R-Ariz.) has called it “one of the great national scandals.” Others have derided it as the “plane that ate the Pentagon.”

One of the planes suffered an engine fire last year that forced the Pentagon to temporarily ground the entire fleet.

But the program has also made significant strides in recent years. Under new Pentagon leadership, the cost has stabilized and key timelines have been met. Last month, the Marine Corps tested its version of the fighter on an amphibious assault ship and said that it performed flawlessly. It was also recently tested flying off a ski jump, which are used on U.K. and Italian aircraft carriers.

The Marines are now on the verge of declaring it combat ready, a huge milestone that could come later this month.

Still, the test pilot who flew it against an F-16 apparently had a different experience: “The F-35 was at a distinct energy disadvantage,” he or she wrote, according to War is Boring.

The unnamed pilot also wrote that “the helmet was too large for the space inside the canopy to adequately see behind the aircraft.”

Pentagon officials said that the particular plane the test pilot flew did not have its special stealth coating, a Harry Potter-like “invisible cloak” that renders it invisible to radar. It was also lacking the sensors that allow “the F-35 to see its enemy long before it knows the F-35 is in the area,” the officials said.

Finally, it didn’t have “the weapons or software that allow the F-35 pilot to turn, aim a weapon with the helmet, and fire at an enemy without having to point the airplane at its target.”

Maneuverability was never going to be the F-35’s main attribute, anyway. It was designed only to be “comparable to current tactical fighters in terms of maneuverability,” Air Force Maj. Gen. Jeffrey L. Harrigian said in the Pentagon’s statement. Its main advantage is its stealth, he said, the ability “to operate in threat environments where the F-16 could not survive.”

While they said they were investigating the leak of the report, Pentagon officials also said “the disclosure of this report should not discourage our warfighters and test community from providing the Program Office and Lockheed Martin with honest assessments of the F-35’s capabilities.”