The top officer of one of three services projected to spend tens of billions of dollars on stealthy new F-35 Joint Strike Fighters, now says "stealth may be overrated."

During a speech last week to a Washington audience, Chief of Naval Operations Adm. Jon Greenert described what he's looking for in the next generation of strike aircraft — and it doesn't look like the controversial F-35.

"What does that next strike fighter look like?" Greenert asked the packed forum. "I'm not sure it's manned, don't know that it is. You can only go so fast, and you know that stealth may be overrated. ... Let's face it, if something moves fast through the air, disrupts molecules and puts out heat — I don't care how cool the engine can be, it's going to be detectable. You get my point."

Greenert was speaking about the next generation of fighter aircraft, but his comments could just as easily be applied to Lockheed Martin's F-35C, the carrier-based version of the joint strike fighter. Aviation analysts who watch the F-35 program closely say Greenert's comments reflect ambivalence among naval aviators about the F-35 as a strike fighter, especially compared to the tried-and-true F/A-18 E/F Super Hornets.

"It's not just Greenert, it's across the naval aviation community: They're just not that into the F-35," said Richard Aboulafia, vice president for analysis at the Teal Group.

Greenert has expressed skepticism about stealth technology's value before, arguing in a 2012 paper that improving computing technology will render even the most stealthy aircraft more detectable.

"Those developments do not herald the end of stealth, but they do show the limits of stealth design in getting platforms close enough to use short-range weapons," Greenert wrote.

"It is time to consider shifting our focus from platforms that rely solely on stealth to also include concepts for operating farther from adversaries using standoff weapons and unmanned systems — or employing electronic-warfare payloads to confuse or jam threat sensors rather than trying to hide from them."

Lockheed Martin, the airplane's prime contractor, doesn't see stealth as overrated, saying in a statement that a stealth aircraft will avoid detection better than a non-stealth aircraft every time, and give it the edge in a fight.

"Stealth provides a huge, almost immeasurable advantage because of adversaries' difficulty in detecting the F-35 by the use of either ground-based or airborne radar ... The F-35 design is balanced to optimize stealth in several dimensions, and integrated sensors provide the pilot exceptional situational awareness and tactical advantages against future threats. No other fighter system provides that level of survivability."

The Navy's wait-and-see approach to the F-35C is evident from its buying strategy, said Aboulafia, the Teal Group analyst.

The Navy ordered two F-35Cs for 2015, which lawmakers doubled to four, would bringing the grand total to 3028 in the first seven years of production, according to budget documents and a inventories cited in the most recent Congressional Research Service Report on the program.

By contrast, the Marine Corps requested six F-35B jump-jet variants and the Air Force requested 26 F-35As, bringing their totals to 66 and 130, respectively.

In the fiscal 2016 budget request, the Navy plans to order four F-35Cs.

In 2013, the Navy proposed buying two F-35Cs in fiscal 2014, but ultimately procured four after their buy was doubled by Congress.

"There are some officers in the Navy who would like to see stealth brought to carriers, but quite a few who wouldn't, who would rather stick with something they know, at a price they know, with two engines that they know and perhaps, shift all funding to the sixth generation [F/A-18]," Aboulafia said.

He said the Navy's buying pattern is telling as to how it sees it integrating into the fleet.

"They are just not acting like the F-35 will be a major part of their force structure in the future," he said, noting he estimated that the Navy might end up buying roughly 200.

The F-35 is the most expensive weapons program in Pentagon history, expected to clock in at about $1.5 trillion over the program's lifetime.

Bryan Clark, a retired commander and a former policy adviser to Greenert, said the F-35's real benefits come from its advanced command-and-control systems, its less-detectable data links and its top-of-the-line intelligence, surveillance and reconnaissance systems.

"These and its stealth would enable it to act as a forward sensor and command-and-control platform. These functions might be more valuable than what it brings from a pure strike perspective," he said.

Ultimately, if the Navy wants it for an ISR platform and a secondary strike fighter, it wouldn't need as many in the future.

"It could change how many it buys long term to field one squadron per carrier air wing instead of two," he said. "The second squadron per air wing could instead be [Unmanned Carrier-Launched Airborne Surveillance and Strike], F/A-18 E/F derivatives, or another aircraft, but they would be intended to deliver larger payloads than F-35."

Staff writer Meghann Myers contributed to this report.