Abstract: Background: Improved understanding of how US service members transition from chronic/baseline to acute suicide risk is warranted. One such model, the Integrated Motivational Volitional Model of Suicide, posits entrapment as central to this process. However, entrapment has not been extensively investigated within military populations. Methods: This study examines the factor structure, reliability, and predictive validity of the Entrapment Scale (E‐Scale) within a military population. Exploratory structural equation modeling (SEM) and confirmatory factor analysis compared one‐ versus two‐factor structures of the E‐Scale. Autoregressive SEM assessed if E‐Scale scores predicted suicidal ideation and suicide attempt likelihood at 6‐ and 12‐month follow‐up, and examined whether the impact of entrapment was moderated by social support (i.e., appraisal, tangible, and belonging). Results: Results favored a two‐factor solution (external and internal) of entrapment. The relationship between entrapment and suicide outcomes was moderated by perceived social support but in unexpected directions. Unexpectedly, social support strengthened the relationship between external entrapment and suicide outcomes for most models. Only tangible support moderated the relationship between internal entrapment (IE) and suicide outcomes as predicted. Conclusions: IE is linked with suicidal ideation in the short‐term, whereas external entrapments relationship with suicide outcomes may reflect more persistent social challenges for military members.