MST is the official phrase for the psychological trauma that may result from sexual assault or repeated, threatening acts of sexual harassment while in the military. In other words, if these experiences occurred while on active duty or active duty for training, they are considered to be MST. MST is the primary causal factor of Post-Traumatic Stress Disorder (PTSD) for women, whereas combat experience is the strongest predictor of PTSD for men (Street et al. 2008).
This is the definition of MST used by the U.S Department of Veterans Affairs (U.S. Code 1720D of Title 38):
MST is "psychological trauma, which in the judgment of a VA mental health professional, resulted from a physical assault of a sexual nature, battery of a sexual nature, or sexual harassment which occurred while the Veteran was serving on active duty or active duty for training." Sexual harassment is further defined as "repeated, unsolicited verbal or physical contact of a sexual nature which is threatening in character."
In more concrete terms, MST includes any sexual activity against the person’s will. Other MST experiences include unwanted sexual touching or grabbing, threatening, offensive remarks about the person’s body or sexual activities, and threatening and unwelcome sexual advances.
The Department of Veterans Affairs (VA) has a system in place to respond to MST including MST screening and treatment, training staff on MST-related issues and outreach to Veterans about available services. Every VA facility has an MST Coordinator who serves as a contact person for MST-related issues. (US Department of Veterans Affairs, National Center for PTSD - Military Sexual Trauma)
DoD Safe Helpline: Department of Defense (DoD) Safe Helpline is a groundbreaking crisis support service for members of the DoD community affected by sexual assault. Safe Helpline provides live, one-on-one support, and information to the worldwide DoD community. The service is confidential, anonymous, secure, and available worldwide, 24/7 by click, call, or text — providing victims with the help they need, anytime, anywhere.