The officers were relieved during a port visit in Guam, and they'll be temporarily reassigned in San Diego pending more possible administrative actions, the Navy Times reported.
Darlak's ouster comes just over three months after he assumed command of the Vandegrift. He previously served as executive officer of the destroyer Stethem.
Capt. H. Thomas Workman, a deputy commander from the ship's squadron, has taken over the Vandegrift until it returns to San Diego at the end of its seven-month deployment later this month, the statement said, and the Navy emphasizes that the ship remains fully ready for any mission.