As the Senate weighed whether to confirm Pete Hegseth as defense secretary, NBC News dug up information about his past, including an affidavit from his former sister-in-law accusing him of abusive behavior toward his second wife. Courtney Kube, a Pentagon correspondent for the network, assisted with the coverage.

The reporting did not upend the confirmation of Mr. Hegseth, a Fox News host before his nomination. But it did leave an impression on him.

Shortly after taking office, Mr. Hegseth told his team to bar Ms. Kube from the Pentagon, according to three people with knowledge of his order. The team did not follow through, because Pentagon lawyers said the Defense Department could not single out one news outlet for removal, two of the people said.

Mr. Hegseth’s request did, however, foreshadow his adversarial approach to the press while in the job — both toward specific reporters and toward the industry more broadly.

Under his leadership, the department has removed national news outlets from a shared media workspace and made it available to conservative outlets instead; has scaled back reporters’ ability to roam Pentagon corridors; and, in the most recent salvo, is imposing a set of restrictions outlining causes for the revocation of correspondents’ press passes.

The Defense Department is falling in line with a policy of hostility toward news organizations that spans the Trump administration. President Trump himself has sued ABC and CBS over their coverage, with both lawsuits ending in settlements, and has accused The Wall Street Journal and The New York Times of defamation. (The case against The Times was dismissed, though Mr. Trump has the right to file a new complaint.) The White House ejected The Associated Press from the White House press pool and seized control of coverage assignments formerly administered by the White House Correspondents’ Association.