Development Of a Virtual Stress Inoculation Training (SIT) Platform and Mobile Health App

Inclusion Criteria: * US Military Veterans / Service Members * diagnosis of PTSD as measured by a Posttraumatic Symptom Checklist for DSM-5 (PCL-5) score of \>33 * history of combat trauma and/or military service in an imminent danger pay area * be fluent in English. * be capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form and in this protocol. * have access to a SmartPhone or tablet to utilize the mobile health app and/OR access the virtual classroom. * agree to undergo psychometric testing and participate in ongoing assessments throughout the study duration. * be willing to comply with all study procedures, able to complete all assessments independently, and available for the duration of the study. Exclusion Criteria: * Active suicidal ideation as assessed by the Investigator at screening or as identified during the study. * Clinically significant history of psychotic disorder, bipolar spectrum disorder, or neurodegenerative disease/dementia as assessed by the Investigator. * Active severe substance abuse as assessed by the investigator in accordance with DSM-5 Substance Abuse Disorder criteria, an AUDIT score \> 15, or partial Brief Addiction Monitor (BAM) indicating the presence of illicit substance use other than cannabis (\< 3 times weekly). * They are currently undergoing another form of treatment other than supportive therapy (\> 2 times per month). * Engaged in active trauma-focused therapy including Cognitive Processing Therapy (CPT)Prolonged Exposure (PE), or Eye Movement Desensitization and Reprocessing (EMDR). * Any other condition/situation that the Investigator believes may interfere with participant safety, study conduct, or interpretation of study data.