Military officials said they would pay about $3.8 billion for 32 of the next generation of radar-evading planes and additional equipment to manufacture and test them.
It was not immediately clear how much each of the jets would cost. Officials said they would provide more details once the deal was completed.
The F-35 is the most expensive weapons program in history. Difficulties in developing some of its complex technologies have contributed to several years of delays. The Pentagon is slowing work on the program to fix the problems, and it now estimates that the program may cost $396 billion if it builds more than 2,400 of the planes.
The new agreement expands a government effort to get tougher on Lockheed, the world’s largest military company, and other contractors as military budgets tighten. With the agreement, Lockheed will share the costs of fixing the flaws that have been uncovered in the flight tests.
The company will now have to pay 50 percent of the cost of some of the retrofit work. That work is needed because the planes are being built even as all the flight and weapons systems are still being checked out.
Both sides want to complete the agreement before the end of the year to minimize…