Boeing, Lockheed Martin executives grapple with President Trump’s personal interest in projects like the F-35, Air Force One, by Doug Cameron.

The public criticism set off efforts to respond at the top reaches of both firms, as surprised executives quickly realized that Mr. Trump’s personal interest in matters such as the cost of Air Force One and the F-35 jet fighter program was changing the rules of engagement, according to people familiar with the situation. …

Defense-industry executives had expected military spending would rise under the Trump administration. During the campaign, Mr. Trump’s stump pledges to boost outlays pushed defense contractors’ share prices to record levels.

The spending pledge remains, but Mr. Trump — through negotiation — is attempting to help pay for it in part by stoking competition and bringing costs down overall in the process. …

At his estate, Mr. Trump grilled his military briefers on the costs and the design of the platforms, seeking to understand why the planes were so expensive, people familiar with his thinking said.

The briefers explained the capabilities of the plane, category by category. Mr. Trump accepted parts of the presentation and rejected others, those people said.