A change in leadership is occurring at the Pentagon, with Navy Secretary John Phelan departing. This move is part of a recent trend of top defense leaders leaving their positions. Details about the circumstances surrounding Phelan's departure are not available in this brief.

For more information, readers can refer to the source. Further details on this development can be found through KHOU Houston, which reported on the Pentagon's announcement regarding Navy Secretary John Phelan's exit.