President Donald Trump this week renewed his questioning of the military's new system for launching aircraft at sea, underscoring his skepticism about a technology the Navy has put at the center of its future aircraft carrier fleet.

In a call to service members on Thursday marking the Thanksgiving holiday, Trump asked the commander of the USS Ronald Reagan, a Nimitz-class aircraft carrier deployed in the Pacific, whether he supported using electromagnetics rather than the traditional steam system to catapult aircraft off carrier decks and land them safely back on board.

"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?"

Trump has repeatedly criticized General Atomics' Electromagnetic Aircraft Launch System (EMALS), installed on the Navy's newest carrier and slated to be used on other new ships. The debut of that system, the culmination of years of testing and development, has been plagued by delays and technical problems.

Capt. Pat Hannifin, articulating the Navy's view, responded by telling Trump that EMALS would lessen the burden that steam-powered systems exact on carriers and was within sailors' power to operate successfully.

"You sort of have to be Albert Einstein to run the nuclear power plants that we have here as well, but we're doing that very well," Hannifin said.

The exchange was the latest in a series of comments that Trump has made challenging Pentagon procurement decisions, illustrating his confidence that he may know more than his military leaders. The Navy did not have an immediate response to the president's comments.

Trump has also suggested he would ditch the military's flagship fighter jet, the F-35, which has suffered from design flaws and come in over budget.

Of the Navy's current fleet of 11 nuclear-powered carriers, only the newest one, the USS Gerald Ford, is equipped with EMALS. Even after its commissioning in 2017, shipboard testing for multiple systems on the Ford has continued, including EMALs.

In the past, problems emerged when EMALS was tested for launching aircraft with wing-mounted fuel tanks. Pentagon reporting has likewise shown that critical failures occurred at a high rate during EMALS testing in 2017. More recent testing on land has been successful, and General Atomics says it expects EMALS and its associated landing system will help ensure the Ford is ready for fleet operations in 2019.

A recent Congressional Research Service report, however, said that EMALS had met reliability requirements only after the Navy lowered its target for the system. "This lower target will also prevent the ship from meeting the program's aircraft launch and recovery requirement," the report said.

Trump has singled the system out before, saying last year that it cost more and was "no good," suggesting the Navy should return to "goddamned steam." More recently, he called the technology "ridiculous" while complaining broadly about the military's desire for new equipment. It's not clear how the president became interested in this somewhat obscure military technology issue.

Despite the president's criticism, the Navy is planning to use EMALS in its future carriers, including three other planned Ford-class ships. The next one, the John F. Kennedy, is scheduled to be delivered to the Navy in 2024.

Navy officials maintain the system is superior because it takes up less room on the ship, reduces wear and tear for carriers and planes, increases the number of aircraft that can be launched, and requires fewer personnel to operate. Over decades, naval officials contend, the system will create significant cost savings.

Unlike the older system, which uses a large, maintenance-intensive system of pipes and pistons to propel planes into flight, EMALS uses a more efficient linear-induction motor and is seen as more suitable for launching an array of aircraft, from drones to heavy jets. Ship builder Huntington Ingalls has likened it to "the system that powers many of today's roller coasters."

While it was not immediately clear how much of the Ford's approximately $13 billion price tag is represented by EMALS and its landing component, they have cost hundreds of millions of dollars to field. Lawmakers and watchdogs have criticized the Navy for failing to produce realistic cost estimates for new carriers and incorporating new technologies that have slowed new carriers' debuts.

China is expected to use a similar system on its future aircraft carriers.

While Trump, in his call Thursday, appeared to accept Hannifin's defense of EMALS, it was not clear whether he will continue to question its value. "I'm actually happy about that answer, because at least, you know, they're doing what they're doing," he said. "But that's actually a very good answer."