US Pentagon, Lockheed agree to deal on ninth lot of F-35 jets: Sources

The US Department of Defense and Lockheed Martin Corp ended negotiations on their ninth contract for F-35 fighter jets after 14 months of negotiations on the more than $6.1 billion deal, people familiar with the talks said on Wednesday.

The unilateral agreement is for 57 of the new war planes in the F-35 programme, the Pentagon's costliest arms programme.

The people spoke under condition of anonymity because they were not authorized to speak about the negotiations on the record. Representatives for the Pentagon and Lockheed did not immediately return requests for comment.