WASHINGTON — Donald Trump’s doubts about the $379 billion F-35 jet, the Pentagon’s largest weapons program, could cast a pall over the defense industry’s early euphoria that a major boost in spending is coming after the next administration takes office.

The stealth fighter built by Lockheed Martin Corp. was the only major weapons program Trump questioned during the campaign, even as he espoused the need for a larger Army and more warships. In an October 2015 interview with radio host Hugh Hewitt, Trump criticized the jet’s costs and said he heard “that it’s not very good. I’m hearing that our existing planes are better.”

He’ll have to decide quickly whether that skepticism still stands.

Soon after taking office in January, Trump will be faced with some key decisions about the F-35 and other weapons systems. Under current plans, the U.S. is scheduled to boost purchases of the jet in the fiscal year 2018 budget to 70 from 63 this year. The number is set to increase further to 80 in fiscal 2019. There’s also a pending “block buy” of 450 aircraft in the coming years as the Pentagon seeks a total fleet of 2,443.

“While Trump may not be a big fan of the F-35, he really has very few other options to modernize tactical combat aircraft,” Byron Callan, a defense analyst with Capital Alpha Partners LLC, said in an e-mail.

Like many expensive weapons systems, the F-35 had been plagued by delays and cost overruns. The Pentagon last month said it will need as much as $530 million extra to finish the fighter’s development phase. Approving the added funds would probably be the first F-35 decision to reach the desk of the next defense secretary.