The Pentagon and Lockheed Martin reached an agreement in principle on Friday on the price of a fifth batch of F-35 fighter jets after a year of tense negotiations over how to lower costs.

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.