Lockheed is the biggest US government contractor, and its F-35 program is America’s most expensive weapons system, worth a projected $379 billion for 2,443 aircraft. The company and the government are currently negotiating a $7.2 billion contract for 90 planes, the government’s biggest order to date, according to Bloomberg. F-35s made up one-fifth of Lockheed’s revenue last year.

Following Trump’s criticism, a Lockheed executive said that the company was trying to cut the cost of an F-35 by 70% from original estimates, according to Reuters.

This is not the first time Trump’s tweets about his administration’s spending priorities hit a company hard on the stock market. After he attacked Boeing last week for the cost of a new Air Force One contract on Twitter, the company’s share price did a similar nosedive.

With additional reporting by Eshe Nelson.

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