Multiple sources told CNN there was tension for months between Phelan and Hegseth, who believed he was moving too slowly on implementing shipbuilding reforms and was also irked by Phelan’s direct communication with Trump, which Hegseth viewed as an attempt to bypass him.

Deputy Defense Secretary Steve Feinberg also wanted to take control of major responsibilities for shipbuilding and navy acquisitions, a job that would typically be within Phelan’s purview.