Background Moral distress is well-documented among civilian critical care nurses and adversely affects patient outcomes, care delivery, and retention of health care providers. Despite its recognized significance, few studies have addressed moral distress in military critical care nurses. Objectives To refine and validate an instrument to assess moral distress in military critical care nurses. Methods This study examined moral distress in military critical care nurses (N = 245) using a new instrument, the Measure of Moral Distress for Healthcare Professionals–Military (MMD-HP-M). The psychometric properties of the refined scale were assessed by use of descriptive statistics, tests of reliability and validity, exploratory factor analysis, correlations, and qualitative analysis of open-ended responses. Results Initial testing showed promising evidence of instrument performance. The Cronbach α (0.94) suggested good internal consistency of the instrument for the overall sample. Scores for the MMD-HP items and the MMD-HP-M items showed a strong, significant correlation (α= 0.78, P < .001). Unique attributes of military nursing that contribute to moral distress included resource access, futile care, and austere conditions. Exploratory factor analysis established a new military-centric factor for question items associated with inadequate training for patient care, providing care in resource-limited settings, and personal exhaustion. Conclusions These results will help guide specific, targeted interventions to reduce the negative effects of moral distress on our military health care providers, especially in terms of readiness for the next global pandemic and retention of these invaluable personnel.