Defense Secretary Pete Hegseth's behavior has become "erratic" and he seems increasingly "insecure" about his job, sources told NBC News.

WASHINGTON—Defense Secretary Pete Hegseth has discharged members of Pentagon advisory boards on defense policy and military technology, adding to the upheaval during his time at the Pentagon, current and former officials said.

Defense Secretary Pete Hegseth has looked to enact a number of reforms during his early days as head of the Pentagon.