President Donald Trump returned to one of his more bizarre concerns about the US military on a call with US service members overseas on Thanksgiving Day.

Talking to a US Navy officer on the phone from his Mar-a-Lago resort in Florida, Trump asked about a pet peeve of his: the catapults aircraft carriers use to launch aircraft.

US aircraft carriers have only a short distance to launch heavy bomb- and fuel-laden planes, so they hook the planes up to a system called a catapult that accelerates them to more than 150 mph to get them airborne from the ship’s deck.

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The US is working on a new aircraft carrier, the USS Gerald R. Ford, and, like with any new ship, has been struggling to field all the new systems. A chief problem for the Ford has been getting the electromagnetic catapults to work.

Older carriers use steam-powered catapults, a technology the US has long had mastered but can now be improved upon.

“So when you do the new carriers, as we do and as we’re thinking about doing, would you go with steam, or would you go with electromagnetic?” Trump quizzed the sailor, putting him in the awkward position of disagreeing with the president or disagreeing with his superior officers.

“Because steam is very reliable, and the electromagnetic, I mean, unfortunately you have to be Albert Einstein to really work it properly,” Trump said. “What would you do?”

“Yes sir, you sort of have to be Albert Einstein to run the nuclear power plant that we have here as well, but we’re doing that very well,” the officer replied. “Mr. President, I would go electromagnetic [catapults] … We do pay a heavy cost to transit the steam around the ship.”

“Good, OK, I like to hear that. I’m actually happy about that answer,” Trump said. “They’re doing what they’re doing, but that’s actually a very good answer.”

US Navy planners say that the electromagnetic catapults can provide a more consistent and powerful boost for launching aircraft and that the catapult shot can be adjusted for individual aircraft, reducing wear and tear.

But Trump, for some reason, hates the idea of electromagnetic catapults.

From Trump’s 2017 interview with TIME magazine:

“You know the catapult is quite important. So I said, ‘What is this?’ ‘Sir, this is our digital catapult system.’ He said, ‘Well, we’re going to this because we wanted to keep up with modern [technology].’ I said, ‘You don’t use steam anymore for catapult?’ ‘No sir.’ I said, ‘Ah, how is it working?’ ‘Sir, not good. Not good. Doesn’t have the power. You know the steam is just brutal. You see that sucker going, and steam’s going all over the place. There’s planes thrown in the air.’

“It sounded bad to me. Digital. They have digital. What is digital? And it’s very complicated; you have to be Albert Einstein to figure it out. And I said – and now they want to buy more aircraft carriers. I said, ‘What system are you going to be -‘ ‘Sir, we’re staying with digital.’ I said, ‘No you’re not. You’re going to goddamned steam. The digital costs hundreds of millions of dollars more money, and it’s no good.'”