Lieutenant Commander S. John Krewer was born in Billings, Montana and raised in Mesa, Arizona. He received his commission from the United States Naval Academy in 2008, earning a Bachelor of Science Political Science. He earned a Master of Public Administration from Villanova University in 2014.
His first sea assignment was onboard USS CURTIS WILBUR (DDG 54) where he served as Ordnance Officer, and Anti-Submarine Warfare Officer. While onboard CURTIS WILBUR, he participated in many forward deployed naval forces exercises under DESTROYER SQUADRON 15 and the GEORGE WASHINGTON Carrier Strike Group. Serving consecutive Forward-Deployed Naval Forces tours in Yokosuka, Japan, he reported to USS JOHN S. McCAIN (DDG 56) as the Training and Administrative Department Head. While serving in JOHN S. McCAIN, Lieutenant Commander Krewer conducted Japan Disaster Relief in support of OPERATION TOMODACHI in response to the 2011 9.0 Magnitude Tōhoku earthquake and tsunami. He served his department head tours aboard USS WAYNE E. MEYER (DDG 108), executing fleet-up orders as Weapons Officer and Combat Systems Officer. While assigned to WAYNE E. MEYER, he conducted three Seventh Fleet deployments in three years. In 2019, as an Individual Augmentee (IA), he served as the J3 Operations Director for the Seventh Fleet United Nations Security Council Resolutions Enforcement Coordination Cell (C7F UNSCR ECC).
Ashore, Krewer served as Associate Professor of Naval Science at Villanova University from 2012-2015 instructing NROTC Midshipmen on Weapons Systems, Engineering Systems, Leadership and Management, Navigation, and Ethics.
Lieutenant Commander Krewer assumed duties as Executive Officer at AEGIS Technical Representative in Moorestown, New Jersey in August 2020.
His decorations include Navy and Marine Corps Commendation Medal with two gold stars, Navy and Marine Corps Achievement Medal with two gold stars, and various unit, campaign and service awards.