President Trump signed a national security memorandum on Thursday directing the Navy to tear out the electromagnetic catapult system used by the Ford class of aircraft carriers and instead return to steam catapults. U.S. officials said the change will likely cost billions of dollars and require a redesign of the affected vessels.

The directive applies to the fourth ship in the class — to be named the Doris Miller — and to every subsequent Ford-class carrier, according to the officials. The first three ships, the Gerald R. Ford, the John F. Kennedy, and the Enterprise, will retain the electromagnetic launch system already installed aboard them.

Top Navy and defense industry leaders have resisted the change for years, the officials said, because of the enormous expense of removing a system integral to the design of the Ford class. Removing the electromagnetic system from the Doris Miller will require a redesign.

The memorandum follows a promise Trump first made in 2017. During a visit to a carrier in his first term, Trump heard a sailor praise the steam system. In a 2017 interview with Time magazine, Trump said he had told the Navy to go back to “goddamn steam.”

Speaking at a conference in Pennsylvania last month, Trump said of the electromagnetic system: “They’re not nearly as good, too complex.”

The cost of the redesign is expected to run into the billions of dollars, the officials said. The memorandum, signed Thursday, directs the Navy to begin redesigning the Doris Miller and all future Ford-class carriers.

Marcus Weisgerber reported from Washington for The Wall Street Journal.