The first rule of flying the world's most advanced fighter jet: Do not push the red button until you absolutely mean to.

As soon as the display appears on the screen in front of me, indicating that I've arrived over the enemy airfield I'm meant to destroy, an oblong icon representing an AIM-120C air-to-air missile goes shooting across my field of vision. "OK," says the Lockheed Martin executive who's letting me fake-fly the F-35 Joint Strike Fighter, "so it looks like you released your weapon a little early." No jokes, thank you.

Any Navy, Marine Corps or Air Force pilot who steps into an F-35 cockpit already knows not to do that. But when they'll actually climb into one of these cockpits is an open question. The Pentagon has stopped predicting when the much-delayed jet will join the military's airfleet. And with a trillion-dollar price tag, the F-35 program is starting to look like the Dom Perignon of fighter aircraft at a time when the Pentagon barely has enough for a shot and a Miller Lite.

This leads Lockheed Martin to welcome journalists into a mock cockpit, which they want to show is idiot-proof. (I quickly prove it's only mostly idiot-proof.) I move my thumb off the dangerous red button on my right joystick, the one that makes the plane climb and turn, and shift my left thumb to one of the toggles on the left one, which makes it take off and accelerate. Now I've got a cursor moving across a cockpit screen filled with icons of planes in front of me and objects below me.

When the cursor stops moving, as if magnetized, and locks onto an icon, the object becomes targeted. Now if I push the red button lurking tantalizingly close to my right thumb, I will destroy it. On purpose.

The ease of use in the cockpit doesn't make the F-35 unique amongst fighter aircraft. But it better work as intended. The F-35 is already an enormously expensive aircraft. And it's increasingly looking like a target itself – a budgetary target.

That's what's lurking in the background of Lockheed Martin's Wednesday afternoon open house for bloggers. The F-35, in development for over a decade, has ballooned to an estimated cost above $1 trillion over its half-century lifespan – Lockheed disputes the sticker price – making it the most expensive weapon mankind has ever created. In March, the Government Accountability Office bemoaned the complications underlying its advanced features, which include over 9 million lines of code for its software, far more than any other aircraft. Last year, 13 new design flaws were discovered, atop concerns that it may not be safe for flight testing.

Looming over all this is the reduced U.S. defense budgets of the 2010s, including a possible additional round of cuts totaling $600 billion over 10 years scheduled to take effect in January. If the F-35 once appeared too big to fail, it doesn't anymore.

And now it also looks like the Navy is wavering on the jet. In April, it put out a call for a next-generation F/A-18 Hornet after the existing Hornets age out, even though the more-advanced F-35 was supposed to take the Hornets' place. Earlier this month, Adm. Jonathan Greenert, the chief of Naval operations, penned an article that cast doubt on the F-35's value. While Greenert didn't explicitly criticize the Joint Strike Fighter, he predicted that adversaries will field more advanced radars that can detect tactical stealth aircraft, requiring the Navy to shift to "long-range sensor, weapon, and unmanned-vehicle payloads instead of using only stealth platforms and shorter-range systems." As Phil Ewing of DoDBuzz remarked, "Greenert's piece removes all doubt about the Navy's continued institutional resistance to F-35 – or at best, it now makes its official support very confusing."

Lockheed Martin has answers for all of that. Its director of the Navy side of the F-35 program, Bob Rubino, points to clarifications from the Navy that it's sticking with the jet. Who knows what the Hornet follow-on will be, Rubino adds; "it could be an F-35 variant." He shows a video of Defense Secretary Leon Panetta pledging the Pentagon's support for the Joint Strike Fighter.

Lockheed Martin points instead to the unique features of the F-35, which it accurately says are ultra-advanced. Its stealthiness isn't a matter of a paint job, it's designed into the jet: Its fuel tanks and weapons are internal, reducing its detectability. Even when it jams enemy communications, which makes it detectable by radar, Lockheed official Steve Callaghan says its "very specific way of jamming" is more like a "big bank of laser pointers" than a floodlight, protecting the aircraft. But all advancements of the F-35 drives up its price, making it look like one of the "luxury-car platforms" Greenert derided in his piece.

To someone who's never flown an airplane, the luxury is perceptible in the cockpit. The screens in front of me provide different data as soon as I press my forefinger on them. It's not like a smartphone – I can't pinch or swipe to get a better view of a target set. But there are touchscreen functions that let me pull up a bigger picture of what I'm fake-flying over and what other aircraft are in the area. LockMart says the cockpit of the F-22 Raptor, the military's other "5th generation" stealth fighter, operates similarly.

Suddenly a trapezoid shows up on my screen. Its position is projected in green on the wall in front of me – a stand-in for the display in the F-35's helmet. Prompted, I move my cursor over to the trapezoid until it locks in with a red boundary line popping up around it. That's an air traffic control tower over my enemy airfield. I mean to destroy it.

I pitch to the right and then pull up until I'm directly over it, as my helmet would tell me if I were wearing it. The software's algorithms know that I'm trying to maneuver into a kill zone, so when I'm there, the red boundary gets sharper. I'm locked in. Time to push the red button. No more trapezoid.

Never having flown before, I have no idea if the cockpit is actually easier to operate than any other aircraft. LockMart wants me to emerge from the simulation thinking the F-35 is cool. It certainly feels like an advanced plane. But that might turn out to be the Joint Strike Fighter's downfall.