This 2012 photo shows the aircraft carrier USS Gerald R. Ford under construction at Huntington Ingalls Industries-Newport News Shipbuilding in Newport News, Va. (Chris Oxley/U.S. Navy via Reuters) (Handout/Reuters)

Huntington Ingalls’s Newport News Shipbuilding division has been awarded a $15.2 billion contract for two Ford-class aircraft carriers, the Navy and the company announced Thursday.

It was the first time in 30 years that the Navy had awarded a multi-ship contract for aircraft carriers, which cost billions of dollars each and take years to build. Executives said the unusual procurement strategy would save taxpayers $4 billion because the multi-ship contract allows the industry to deploy its workforce more efficiently.

“What we’ve worked on with the Navy is that if you want to take the cost out of building an aircraft carrier we have to get away from building them one at a time,” said Jennifer Boykin, president of Newport News Shipbuilding. “When you know you’re going to build two, you can maximize savings in the production line.”

The Ford-class carrier is a nuclear-powered aircraft carrier that serves as a successor to the Nimitz-class carriers designed in the 1960s. The new ships are designed to increase the rate at which aircraft can take off, and rely on new technologies such as a magnetic field designed to propel aircraft off the ship. And the ship is designed to function with a smaller crew, thanks to advances in automation.

But the Ford class has seen its share of procurement issues, with the late Senate Armed Services Committee Chairman John McCain (R-Ariz.) calling the program “one of the most spectacular acquisition debacles in recent memory.” At about $13 billion, the first ship blew past congressionally imposed caps designed to rein in the Ford’s spiraling costs.

And it experienced numerous technical shortfalls that the Navy and Huntington Ingalls are still working to remedy. Bloomberg News reported last year that the USS Gerald R. Ford was delivered without 11 advanced weapons elevators needed to lift bombs onto the deck of the ship. Boykin described the first Ford-class carrier as a “prototype” because of the new technology it called for.

For the Navy, the block-buy acquisition is a small step toward its goal of attaining a 355-ship Navy by the mid-2030s. President Trump promised on the campaign trail and early in his presidency that he would rebuild the Navy’s fleet above the 350-ship mark. The Navy’s fleet has hovered between 270 and 290 ships in recent years.