(CNN) Defense giant Lockheed Martin has agreed to sell 90 new F-35 fighter jets to the US Defense Department for $8.5 billion -- a deal that amounts to more than $700 million in savings over the last batch of aircraft delivered.

Lockheed Martin credited President Donald Trump for helping to "accelerate negotiations" and "drive down the price" of what is already the most expensive weapons program in history.

The cost of the F-35 Joint Strike Fighter program found itself in Trump's crosshairs on several occasions in recent weeks and Trump called for a review of whether a modified version of the older F/A-18 aircraft could replace the Navy's costly F-35 variant.

Lockheed Martin CEO Marillyn Hewson gave then-President-elect Trump her "personal commitment" to cut the cost of the stealthy F-35 fighter jet after Trump posted a tweet criticizing the program and newly confirmed Defense Secretary James Mattis ordered the Pentagon to conduct a review of the $400 billion program last week.

Once official, the deal in principle would mark the first time that costs for any of the three versions of the fifth generation fighter jet will have dipped below $100 million per plane.

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