In August, President Trump directed the Navy to figure out how to return to using steam catapults on aircraft carriers to hurl fighter jets into the air. For U.S. military officials, the order marked the return of an old foe: Bill Jones. Who? Exactly. Trump has described the man as a “catapulter” who served in the Navy for 25 years and loves the smell of steam. Jones convinced Trump the old technology was superior to modern methods of launching jets, the president said.

The incident sent Navy leaders searching for Jones to figure out what he said that prompted the president to demand an overhaul of one of the most expensive weapons programs in history. They never found him, according to defense officials. But they’re still dealing with the consequences of the mystery sailor and his chance encounter with the president. It all started just months into Trump’s first term when he was in Virginia touring the USS Gerald R. Ford, the newest aircraft carrier in the Navy’s fleet.

This warship, the largest in the world and first in its class, cost about $19 billion but had experienced myriad problems over eight years of construction as cutting-edge, but unproven, technology was installed on the ship. It was years behind schedule and billions of dollars over budget. Trump seemed eager to apply his real-estate experience to the dazzlingly complex world of Pentagon procurement. He has said he grew tired of hearing excuses from the admirals and he wanted to hear from the people who operate the machinery.“I said, ‘Let me see the catapult people,’” Trump recalled during an April 2019 speech.

“They said, ‘Sir, you don’t really want to do that?’ I said, ‘Yeah, those are the people that know what the hell they’re doing.’”Then it happened. The president said a sailor told him the Navy was making a mistake by ditching the tried-and-true method of using steam catapults.

The decision to use an electromagnetic system to launch planes faster and more efficiently was dooming the service to failure. The USS Abraham Lincoln uses a steam catapult to conduct flight operations in the Arabian Sea. (US Navy)Trump has said the sailor told him if the electric catapults break you need geniuses from MIT to repair them, while the steam version can be fixed with a hammer and blowtorch. Industry officials said both descriptions vastly oversimplify things.

After the encounter, Navy officials scrambled to explain to the president why the technologies were chosen and why removing them would be extremely disruptive, according to former defense officials. During a Thanksgiving call in November 2018 to sailors aboard the USS Ronald Reagan, an older Nimitz-class carrier with steam catapults, Trump asked the ship’s commanding officer his opinion of steam versus electric catapults. Then-Capt. Patrick Hannifin, now a three-star admiral in charge of naval forces in the Western Pacific and Indian Oceans, told Trump that while steam is reliable now, he preferred electromagnetic catapults.

When Trump pressed Hannifin that “you have to be Albert Einstein” to operate them properly, the captain responded: “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.”Trump said “that’s actually a very good answer.”The issue seemed to go away. It came roaring back as Trump sought and won re-election. He mentioned Jones by name during a January 2024 rally in Mason City, Iowa.

Then in February 2025, Trump brought up the electric catapults when he swore in Tulsi Gabbard to be the director of national intelligence. There were rumors among industry insiders that Trump would sign an executive order telling the Navy to return to steam, but nothing happened—until this summer. In August, Trump signed a national security memorandum directing the Navy to figure out the cost and timeline for installing steam catapults and hydraulic elevators in the ship currently known as CVN 81, expected to join the fleet in 2034.

The Navy isn’t getting its Ford-class carriers fast enough, and must simplify their design by using time- and battle-tested technology, an administration official said. It hasn’t built a carrier with steam since the USS George H.W. Bush, which entered the fleet in 2009. More problematic: “Steam catapults have been out of production for decades—no one makes them anymore,” said Hunter Stires, the maritime strategist to former Navy Secretary Carlos Del Toro.

Since the order, Navy leaders have couched their public remarks.“If we were to go back to steam and hydraulics with the elevators, we need to really understand the total cost of that,” Chief of Naval Operations Adm. Daryl Caudle said at a conference in Reno, according to USNI News. “That will be a significant design change.”He said a February stress test of the Ford’s electromagnetic launchers showed they outperformed their steam peers.

An aircraft taking off via electric catapult on the USS Gerald R. Ford in January 2020. (Marcus Weisgerber/WSJ)Analysts and industry insiders say the new system could be more effective for future warfare since it could launch bomb-laden aircraft and drones. Shipbuilding experts worry putting steam back on a carrier would put the Navy technologically behind China. Acting Navy Secretary Hung Cao has warned officials not to question the president’s decision.“To be clear, the debate on whether we do this has ended,” he wrote in an Aug. 28 memo, referring to a broader set of recommendations including the steam catapults.

“Our task now is to provide the plan on how to implement.”Given the ship won’t be completed before Trump is set to leave office, and Democrats are expected to gain control of at least one chamber of Congress in the midterms, the chance that a new ship with the old catapults actually joins the fleet drops significantly. Still, the Navy is steaming ahead.“This could ultimately be a multibillion-dollar change that was resulting from largely this one sailor’s interaction with the president,” said Bryan Clark, a naval expert with the Hudson Institute, a Washington think tank.

“Which is kind of crazy when you think about the level of impact a single person had.”Trump has gotten personally involved in several other projects, from the new Air Force One and a class of high-tech battleships to a futuristic military drone port on the top of the White House. In an attempt to find the mysterious Bill Jones, The Wall Street Journal contacted current and former Navy officials, lawmakers, White House aides and industry executives. No one who was contacted knows the sailor’s identity.A Navy spokesman said that without his date of birth or other identifying information, it “cannot accurately locate this Sailor in our records.”

Write to Marcus Weisgerber at marcus.weisgerber@wsj.com