Lockheed Martin Corp on Monday confirmed that it had delivered just 22 of 36 F-35 fighter jets promised to the U.S. government this year, but had a plan to complete work on the remaining 14 warplanes over the next two months.

“We are not giving up on delivering 14 more aircraft this year,” Lockheed spokesman Mike Rein told Reuters when asked about delays in deliveries. “We’ll get there.”

A source familiar with the $399 billion Joint Strike Fighter program, the Pentagon’s costliest weapons project, said slower-than-expected deliveries had sparked concern about whether Lockheed would meet its delivery target of 36 jets for the full year. The company could lose incentive fees if it does not, said the source, who was not authorized to speak publicly. […]