Donald Trump took aim at the Pentagon’s costliest program on Monday, saying on Twitter the “program and cost” of the F-35 Joint Strike Fighter “is out of control.”

This is the second defense program in recent days the president-elect has unloaded on for cost issues. Last week, Mr. Trump claimed the government’s second-largest defense contractor, Boeing Co., had run up costs in the development of new Air Force One aircraft. The developer of the F-35 program is the government’s largest defense contractor, Lockheed Martin Corp.

...