Lieutenant Colonel Hasseltine was commissioned in May 1997 upon graduation from the Virginia Military Institute. After completing the Basic Officer and Infantry Officer Courses, he was assigned to 3d Battalion, 8th Marines serving as a Rifle Platoon Commander, Battalion Adjutant, Company Executive Officer, and Company Commander during deployments to the Mediterranean and Far East. 
  
Lieutenant Colonel Hasseltine reported to The Basic School for instructor duty in August 2001 where he served as the primary instructor for Military Operations in Urban Terrain and Squad Tactics, a Staff Platoon Commander, and Company Executive Officer. In October 2003, he was reassigned as Aide-de-Camp to the Commanding General, Training and Education Command. He was a distinguished graduate of Expeditionary Warfare School for the 2004-2005 Academic Year.
 
In May 2005, Lieutenant Colonel Hasseltine reported to 2d Battalion, 7th Marines where he initially served as the Assistant Operations Officer before assuming command of Fox Company. He commanded the company through two combat deployments to Iraq.

In December 2007, he assumed duties as the Commanding Officer, Recruiting Station Albuquerque, New Mexico. In August 2010, he reported to the U.S. Naval War College as a student in the College of Naval Command and Staff, earning a M.A. in National Security and Strategic Studies with Distinction. 

In July 2011, he reported to 2d Battalion, 5th Marines, where he served as the Executive Officer through the battalion's combat deployment to Afghanistan.  In January 2013, he was assigned to I Marine Expeditionary Force G-3 Future Operations as the Exercise Officer.

His operational experience includes OPERATION ALLIED FORCE (Serbian air war-Adriatic Sea), JTF SHINING HOPE (Kosovar refugee assistance-Albania), OPERATION JOINT GUARDIAN (Peace enforcement operations-Kosovo), OPERATION AVID RESPONSE (Humanitarian relief operations-Turkey), OPERATION EASTERN ACCESS (Support to US Federal Law Enforcement- Vieques Island), OPERATION IRAQI FREEDOM 04-06.2 and 06-08.2 (Counter-insurgency operations- Fallujah, Iraq), and OPERATION ENDURING FREEDOM 12.1 (Counter-insurgency operations – Musa Qal'ah & Now Zad, Afghanistan).

His personal awards include the Bronze Star (with Gold Star in lieu of second award), Purple Heart, Meritorious Service Medal, Navy Commendation Medal (with Combat Distinguishing Device and Gold Star in lieu of second award), Navy Achievement Medal (Gold Star in lieu of second award), and the Combat Action Ribbon (Gold Star in lieu of second award).

He holds a BA in History from the Virginia Military Institute, a Post-Graduate Certificate in Strategic Intelligence from the Joint Military Intelligence College, and an MA in National Security and Strategic Studies from the Naval War College.