Donald Trump on Monday widened his attack on defense contractors, slamming Lockheed Martin Corp's F-35 fighter jet program as too expensive as aides to the president-elect said he intends to keep pushing to cut the costs of military hardware.

Trump's latest Twitter broadside sent defense shares tumbling and fanned concerns that the incoming administration will reduce defense contractors' profit margins and cut broader federal spending, threatening U.S. factory jobs even as Trump promises to boost manufacturing employment.

"The F-35 program and cost is out of control," Trump said on Twitter, echoing campaign promises to cut waste in federal spending. "Billions of dollars can and will be saved on military (and other) purchases after January 20th."