This month, a network of pro-Russian websites began a campaign aimed at undermining confidence in the U.S. defense industry, according to disinformation analysts.
The F-35 fighter jet was one target. The effort, coordinated by a Russian group known as Portal Kombat, spread rumors that American allies purchasing the warplanes would not have complete control over them, the analysts said.
In the past, U.S. cybersecurity agencies would counter such campaigns by calling them out to raise public awareness. The F.B.I. would warn social media companies of inauthentic accounts so they could be removed. And, at times, U.S. Cyber Command would try to take Russian troll farms that create disinformation offline, at least temporarily.
But President Trump has fired General Timothy D. Haugh, a four-star general with years of experience countering Russian online propaganda, from his posts leading U.S. Cyber Command and the National Security Agency.
The F.B.I. has shut down its foreign influence task force. The Cybersecurity and Infrastructure Security Agency has ended its efforts to expose disinformation. And this week the State Department put employees who tracked global disinformation on leave, shutting down the effort that had publicized the spread of Chinese and Russian propaganda.
Almost three months into Mr. Trump’s second term, the guardrails intended to prevent national security missteps have come down as the new team races to anticipate and amplify the wishes of an unpredictable president. The result has been a diminished role for national security expertise, even in the most consequential foreign policy decisions.