In an interview with Time excerpted online Thursday morning, president Donald Trump covered an array of topics. None of his statements has proved more baffling, however, than his claims about catapults aboard USS Ford-class aircraft carriers, the first of which should be in service this summer. Yes, catapults. His remarks on the topic are worth quoting in full:

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 going to goddamned steam, the digital costs hundreds of millions of dollars more money and it’s no good.

Why, you might reasonably ask, does an aircraft carrier need catapults? And what’s the difference a between steam catapult and a “digital” one? Glad you asked!

You first have to understand that Trump wasn’t talking about medieval siege engines, though you’d barely know that from reading his comments. Instead, the key is in his offhand claim that his interlocutor said something about “planes thrown in the air.” Despite their size, aircraft carriers have relatively short runways. Accordingly, they employ catapult systems to help assist with takeoff.

For decades, the steam-powered launch system that Trump alludes to have been the norm. Despite its antiquated-sounding name, these catapults are complicated mechanisms, not some sort of Victorian holdout. Illumin offers a helpful gloss of the way it all works, but it goes something like this: When they’re preparing for launch, planes are strapped into the catapult, holding them in place, even as their pilots are throttling their engines. When the steam—drawn, as Defense Industry Daily explains, from a carrier’s nuclear reactor—accumulates, it activates pistons in the catapult, removing the restraints and sending the aircraft hurling forward and into the sky. Fwoosh!

It’s an effective system, which is why it’s been employed for so long, but it’s not without its problems. As Defense Industry Daily notes, “The result is a large, heavy, maintenance-intensive system that operates without feedback control; and its sudden shocks shorten airframe lifespans for carrier-based aircraft.” In addition to increasing wear-and-tear, steam-based catapults may not be ideal for future generations of aircraft, some of which may be too heavy for the system to support them.

Enter the Electromagnetic Aircraft Launch System, generally known as EMALS. (Yes, really.) This new system—which is presumably what Trump had in mind when he spoke of “the digital”—really is complicated, but the basic function is simple enough: In fact, it’s reportedly similar to the technology used on rollercoasters. EMALS works by activating a series of motors that pull the aircraft along a track, helping it reach its appropriate speed as it accelerates. The process puts considerably less stress on aircraft, meaning that they can remain operational for far longer. It’s also faster and allows for more precise calibrations, allowing carriers to quickly launch a variety of aircraft

I called up defense expert Peter W. Singer of New America (which is a partner with Slate and Arizona State University on Future Tense) who affirmed the potential benefits of EMALS. “They offer you improved efficiency and are less maintenance intensive. It allows the aircraft carrier to operate more effectively, because the turn-around time is better,” he said. He also pointed out that China will likely incorporate EMALS-type technology into the generation of aircraft carriers after the one they’re currently developing.

“Trump doesn’t know what he’s talking about. That technology is a key selling point of the new aircraft carriers,” Singer said.

One of the most puzzling elements of Trump’s statement is his description of the catapults as “digital” rather than electromagnetic. It seems entirely possible, of course, that Trump—who, as we have long known, understands terrifyingly little about computers—simply flipped the two words. Indeed, his assertion that “you have to be Albert Einstein to figure it out” squares well with his previous claims about hacking and other problems with what he has called “the cyber.”

That said, it’s worth noting that the underlying digital complexity of EMALS is one of its selling points. According to a post on the site Global Security, “Another advantage of EMALS is that it would reduce manning requirements by inspecting and troubleshooting itself.” While it would demand that crews be taught new skills as they learn to interact with the new system, it presumably wouldn’t require whole teams of Einsteins, thanks in part to its self-diagnostic capabilities.

Why, then, would Trump want to abandon this promising new technology just before it goes into operation? If we take him at his word, it’s presumably because the system is pricier than the older alternative. There may be some truth to this claim: The Ford-class carrier program has been dogged by delays and cost overruns. But as the Atlantic notes, “[T]he problems with the Ford-class carrier program are more organizational than technological.” What’s more, Navy Times cites an estimate indicating that EMALS will “save the Navy $4 billion in maintenance costs over the course of the ship’s 50-year lifetime.”

Further, Foreign Policy’s Robbie Gramer points out that this proverbial ship has already sailed, even if the USS Ford hasn’t. “Experts say it’s virtually impossible to sort out how to replace the existing EMALS system with the old steam-powered system, and that could cost billions of dollars,” Gramer writes. In other words, Trump’s attempt to save money could cost the military dearly, even as it restricts its capacity for technological development in other ways.

Singer echoed many of these concerns in our conversation. “For people who know this topic of defense acquisitions one of the reasons you get escalating costs is when you change the requirements and designs midstream, and that’s exactly what [Trump’s] proposing to do here,” he told me. Moreover, he noted, “This is inappropriate, and an amazing level of micromanagement that would have Republican defense wonks apoplectic if Obama had done it.”

They don’t seem to be objecting yet.