WASHINGTON — President-elect Donald Trump again took to Twitter on Thursday to question the cost of the F-35 fighter jet, advocating for modernization of a fourth-generation Boeing alternative that experts say would not likely be possible.



"Based on the tremendous cost and cost overruns of the Lockheed Martin F-35, I have asked Boeing to price-out a comparable F-18 Super Hornet!" he tweeted at 5:26 p.m. EST.



Based on the tremendous cost and cost overruns of the Lockheed Martin F-35, I have asked Boeing to price-out a comparable F-18 Super Hornet! — Donald J. Trump (@realDonaldTrump) December 22, 2016

Lockheed Martin stock, which had closed at $252.80 a share, tumbled down to $247.75 at about 7 p.m. EST, a 2 percent decline. At the same time, Boeing stock shot up by about 1.49 percent, increasing from $157.46 to $158.95 a share.

What this means for Lockheed Martin and its top competitor Boeing in the long term is not exactly clear. Although the F-35 has been plagued with its share of cost overruns and technical issues, the F/A-18E/F Super Hornet is a fourth-generation plane that lacks many of the capabilities that define a fifth-generation plane, such as stealth and sensor fusion. Redesigning a Super Hornet to meet the same requirements as the F-35 would require years of development and engineering time and probably billions of dollars.

"We have committed to working with the president-elect and his administration to provide the best capability, deliverability and affordability across all Boeing products and services to meet our national security needs," said Boeing spokesman Todd Blecher.

Speaking to Defense News at the Reagan National Defense Conference on Dec. 3, Boeing Defense head Leanne Caret expressed confidence that the F/A-18 line would expand out "well into the mid-2020s and beyond. ... I feel very comfortable with where we are with this line."

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A spokesman for Lockheed Martin declined to comment on the tweet, as did a spokesman for F-35 engine manufacturer Pratt & Whitney.

F-35C Lightning IIs and F/A-18E/F Super Hornets fly over Naval Air Station Fallon's (NASF) Range Training Complex on Sept. 3, 2015, in Nevada.

Photo Credit: Lt. Cmdr. Darin Russell/US Navy

Richard Aboulafia, an aerospace analyst with the Teal Group, said Trump’s tweet reflects "an interesting debate," albeit one from years ago.

"For the Navy, at least, he’s not wrong about the plan," he said. That service has limited its F-35C buys while continuously adding money into its budget for Super Hornets and its electronic warfare-capable brother, the E/A-18 Growler, which is manufactured on the same production line.

But "eventually somewhere towards the tail end of this administration, the Navy will have to shift to the C," he said.

Aboulafia also acknowledged the difficulty of transforming an aircraft like an F/A-18 into a fifth-generation fighter. Super Hornets "are strike aircraft for a carrier deck. It’s a useful strike fighter for a large carrier, but its fundamentally a different aircraft. You can’t just make it stealthy," he said.

Earlier this week, Lt. Gen. Christopher Bogdan, the F-35 joint program office chief, charted the progress of the program since it hit a Nunn McCurdy breach and was rebaselined in 2011. Since then, Bogdan said Monday, the F-35 program had operated mostly on schedule and mostly on cost, although he acknowledged that the end of developmental flight tests could be delayed by as much as seven months. The program also will likely need $532 million to finish development.

"If anybody would have told us in 2011 that we would be within a few months and a couple hundred million dollars of a $13 billion re-baseline, we’d all slap the table and say, 'We’d take it!'" he said.

"This program is not ‘out of control,’" he added, referencing an infamous Trump tweet from earlier this month that claimed just that.

Bogdan then met with Trump on Wednesday to talk over the F-35 program. Boeing head Dennis Muilenburg

and

Lockheed CEO Marillyn Hewson also had their own meetings with the president-elect.

Muilenburg framed the conversation as favorable, saying that they were "very productive" and that he was "really encouraged" by the "good, open discussion," according to pool reports.

Hewson declined to give a statement, but Trump offered his own take:

"We’re just beginning, it’s a dance. It’s a little bit of a dance. But we’re going to get the costs down and we’re going to get it done beautifully."