Lockheed Martin CEO Marillyn Hewson said on Friday that she has promised President-elect Donald Trump she will drive down the cost of the F-35 fighter jet following a tweet he sent earlier this week. "Based on the tremendous cost and cost overruns of the Lockheed Martin F-35, I have asked Boeing to price-out a comparable F-18 Super Hornet!" Trump tweeted on Thursday. Hewson said in a statement that she has received his message "loud and clear" and that they had a "very good conversation" about the issue. "I gave him my personal commitment to drive the cost down aggressively," she said. The F-35 has stealth capabilities that outmatch Boeing's F-18, an older generation of aircraft. "Somebody needs to ask Donald Trump how he's going to be able to confront China without aircraft capable of penetrating anti-access and area denial systems, including air defenses," an unnamed U.S. official told Reuters. The two models are, according to most defense analysts, not comparable.