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COS General Information

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Combat and Operational Stress (COS) includes all the physiological and emotional stresses encountered as a direct result of the dangers and mission demands of combat.  Combat and Operational Stress Control (COSC) in the U.S. Army may be defined as programs developed and actions taken by military leadership to prevent, identify, and manage adverse Combat and Operational Stress Reactions (COSR) in units.  This program optimizes mission performance; conserves the fighting strength; and prevents or minimizes adverse effects of COSR on Soldiers and their physical, psychological, intellectual, and social health.  Its goal is to return Soldiers to duty expeditiously.  COSC activities include routine screening of individuals when recruited; continued surveillance throughout military service, especially before, during, and after deployment; continual assessment and consultation with medical and other personnel from garrison to the battlefield.

Combat and Operational Stress Control is one of the 10 identified Medical Battlefield Operating Systems (Medical BOS), which includes: Command Control and Communication, Hospitalization and Surgery, Preventive Medicine, Veterinary Services, Laboratory, Blood, Dental Services, Health Service Logistics, Combat Stress Control, Patient Evacuation and Regulation, and Area Medical Support.

The effects of Combat and Operational Stress are experienced by ALL Soldiers spanning every type of military operation in both peace and war.  COSR is not restricted only to combat operations but may also occur as a result of combat like conditions present throughout the entire spectrum of military operations.  These operations range from training, all phases of deployment, peacekeeping, humanitarian missions, stability and reconstruction, government support missions, and those missions that may include weapons of mass destruction (WMD) and/or chemical, biological, radiological, nuclear and explosive (CBRNE) weapons.

The goal of COSC is to enhance unit cohesion and combat capability in the face of high stress operational environments and maximize posttraumatic growth (PTG), a phenomenon in which positive outcomes occur among survivors of a wide range of traumatic experiences, such as car accidents, fires, sexual abuse/assault, military combat, and being held as a refugee.  Posttraumatic growth among trauma survivors has included improved relationships, renewed hope for life, an improved appreciation of life, an enhanced sense of personal strength, and spiritual development.

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  • Combat and Operational Stress:
    • The sum of the physical and emotional stressors experienced due to Combat or extended operations.
  • Combat and Operational Stress Reactions (COSR):
    • The broad group of physical, mental and emotional signs that result from Combat and Operational Stress.
  • Combat and Operational Stress Reaction Casualty (COSR Casualty):
    • Refers to a Soldier who is combat ineffective due to COSR.

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Military leaders, Soldiers and medical providers must understand the difference between COSR and PTSD.  COSR is NOT the same as PTSD.  COSR represents the broad group of physical, mental, and emotional signs that result from Combat and Operational Stress exposure.  COSR is considered a sub-clinical diagnosis with a high recovery rate if provided appropriate attention and time.  Post Traumatic Stress Disorder (PTSD) is an anxiety disorder associated with serious traumatic events and characterized by such symptoms as survivor guilt, reliving the trauma in dreams, numbness and lack of involvement with reality, or recurrent thoughts and images.  PTSD is a clinical diagnosis as defined by the Diagnostic & Statistical Manual of Mental Disorders (DSM IV-TR) and the International Statistical Classification of Diseases and Related Health Problems (ICD 10).  PTSD is one of many possible long term outcomes resulting from Combat and Operational Stress exposure and collectively classified as Long Term Stress Reaction (LTSR).  COSR and PTSD may share some common symptoms in presentation, however, COSR is recognizable immediately or shortly after exposure to traumatic events and captures any recognizable reaction resulting from exposure to that event or series of events.  PTSD has specific chronological requirements and symptom markers that must be satisfied in order to diagnose.  PTSD is only diagnosable by a trained and credentialed healthcare provider.  Military personnel and providers must focus their efforts on the management of COSR and mitigating factors to control COSR in an effort to shape the long term reaction of their organization and individual Soldiers.

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Combat and Operational Stress Control as a Leader Function

Combat and Operational Stress Control is the military commander's responsibility at all levels.  The commander is assisted with his responsibility for COSC by his staff, unit leaders, unit chaplain, and organic medical personnel.  The commander may also receive assistance from organic COSC personnel at brigade and above, and from corps and above medical company/detachment COSC BH personnel.  The key concern to combat commanders is to maximize the return-to-duty (RTD) rate of Soldiers who are temporarily impaired or incapacitated with stress-related conditions or diagnosed behavioral disorders.  The purpose of COSC is to promote Soldier and unit readiness by:

  • Enhancing adaptive stress reactions.
  • Preventing maladaptive stress reactions.
  • Assisting Soldiers with controlling COSRs.
  • Assisting Soldiers with behavioral disorders.

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Risk Factors

Soldiers are at risk for stress reactions just like any other individuals, no matter how seasoned or experienced.  Risk factors are those things that increase the probability that stress will turn into a serious mental health problem.  Risk factors also make Combat and Operational Stress Reaction (COSR) more likely.  The presence of risk factors does not automatically mean someone becomes debilitated by stress, but it raises that risk.  Many of these risk factors can be modified, reduced, or eliminated.  The following risk factors have been associated with a stress reaction:

  • Length of exposure to combat or operational stress.
  • Severity of combat or operational stress experience.
  • History of previous traumatic events (war, child sexual abuse, assault).
  • Previous mental health problems.
  • Alcohol abuse or dependence.
  • Lack of support system or unit cohesion.

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Cohesion, or the bonds between Soldiers, traditionally has been posited as the primary motivation for Soldiers in combat.  Unit cohesion and morale is the best predictor of stress resiliency within a unit or organization.  Units with high cohesion tend to experience a lower rate of COSR casualties than those with low cohesion and morale.  High cohesion and morale enhance adaptive stress reactions in Soldiers and organizations.  Esprit de corps is the one major entity that can transcend the problems of race and prejudice.  The upkeep of morale and cohesion in combat are recognized as vital elements in the production of combat power in tactical units.  Supportive leadership always matters.  Whether a Soldier has been to combat or not, supportive leadership is related to how Soldiers are doing, both at a personal level (personal morale) and at a unit level (unit morale, cohesion, & combat readiness).  This is good news for the military, because leaders can be trained to be more supportive of their Soldiers and therefore, improve the chances of the Soldiers having higher personal morale, higher unit morale, better unit cohesion, and higher perceptions of combat readiness.  Today's U.S. Soldiers, much like Soldiers of the past, fight for each other.  Unit cohesion is alive and well in today's Army.

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Why Soldiers May Not Seek Help

  • Feeling as though any psychological issues within themselves or others is a sign of weakness.
  • Expressing an emotional reaction may be confronted with, "suck it up" or "get over it".
  • Fear that emotional reactions will negatively impact their careers.
  • Fear that getting help will negatively impact their careers.
  • Fear of their commander having complete access to mental health records.
  • A command climate that discourages getting help.

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Unit cohesion and morale is the best predictor of stress resiliency within a unit or organization.  Units with high cohesion tend to experience a lower rate of COSR casualties than those with low cohesion and morale.  High cohesion and morale enhance adaptive stress reactions in Soldiers and organizations.  The foundation for any stress reduction program includes trust and confidence in the following—

  • Leaders.
  • Training.
  • Unit.
  • Equipment.


Leaders must demonstrate effective leadership to earn their subordinates' confidence, loyalty, and trust.  Leaders are responsible for—

  • Committing the unit to missions commensurate with abilities.
  • Planning operations carefully and thoroughly.
  • Preparing the unit to accomplish the mission.
  • Leading and guiding the unit to mission accomplishment.
  • Showing consistent good leadership that convinces subordinates their leaders know best what should be done, how it should be done, who should do it, and how long the task should take.  Authority accompanies leadership beyond the automatic authority given by military rank and position.  Authority and respect are earned based on confidence in a leader's ability to guide the unit to success.


Training helps Soldiers develop the skills required to do their jobs.  Confidence is the result of knowing they have received the best possible training for combat, and are fully prepared.  This confidence results from the following:

  • Realistic training that ends with successful mastery.
  • Relevance of training to survival and success on the integrated battlefield.
  • Refresher and cross training.
  • Systematic individual and collective training.


Each Soldier in a unit needs to become confident of the other unit members' competence. Individuals must stay and train together to gain that personal trust.  Unless absolutely necessary, teams should not be disbanded or scrambled.  Subunits in the same larger unit should have the same standard operating procedures (SOPs) and training standards, so members can fit in quickly if teams have to be cross-leveled or reorganized after casualties occur.  History has shown that most Soldiers "stay and fight" primarily as a direct correlation to the bonding and identity they have established with unit personnel.  Soldiers fight for the battle buddy next to them.  It is imperative that leadership make every effort to develop this relationship in a healthy, cohesive way to insure unit integrity in high stress environments.

Mission accomplishment is the unit's highest priority.


Soldiers who learn to operate and maintain assigned equipment develop confidence in their ability to employ it.  This, in combination with an individual's belief in his personal capabilities, raises overall confidence in his fighting ability.

Leaders Must:

Educate your Soldiers.  Provide accurate information to your Soldiers so they have appropriate expectations and will be psychologically prepared for the effects of combat and extended or intense operations.  The Battlemind Training System is designed to do this.  Transmit information through the chain of command on a routine basis so that Soldiers rely on official sources rather than rumors.  Information about mission background, rules of engagement, length of deployment, culture of the host country, rival factions, and disease threat will give Soldiers a concrete focus for plans and actions.

Continue training.  Training for current and future missions should not stop in country.  Well-learned and practiced skills are less disrupted by stress.  Realistic training builds confidence, improves cohesion and prevents boredom.

Live as a team.  Encourage Soldiers to handle issues (lack of privacy, personality conflicts, alienation, etc.) early, openly, and as a team.  A simple self-check and buddy-check system can identify and reduce the incidence of Combat and Operational Stress Reaction (COSR) and increase overall unit effectiveness.

Maintain unit cohesion.  Cohesive, well-disciplined units have fewer stress reactions.  Soldiers should routinely debrief each other after an operation, and discuss what they saw and how they felt.  Soldiers who have strong emotional reactions to Potentially Traumatizing Events should be kept with the unit and treated as Soldiers and not casualties.

Manage contact with the injured, dying, and dead.  Soldiers who are caring for sick or injured refugees should have opportunities to take regular breaks away from the action.  Soldiers who handle corpses should insulate themselves from the task by not looking at faces and not learning names or other personal information about the dead.  Soldiers should put mental and physical barriers between themselves and the deceased and finish jobs quickly.  Soldiers who say they cannot handle such duty should be excused whenever possible.  Personnel should work in pairs; experienced Soldiers should be paired with inexperienced ones.

Schedule recreation.  Maintain physical fitness and engage in recreational activities to reduce stress.  Recreational activities that include units of multinational forces will also serve to introduce Soldiers to each other and prevent friction.

Deliver mail.  Ensure that the unit's system for distributing mail is quick, efficient, and effective.  In particular, distribute pay vouchers in a timely manner.

Allow decompression time.  Soldiers need time to relax and adjust to normal routines upon redeployment.  However, it is important, and required by regulation, that the decompression time initially be accomplished by working half days on station prior to releasing them on their own.  This policy is particularly important toward reducing domestic violence incidents.

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Suggested Resources

Battlemind Training Modules (https://www.battlemind.army.mil/) External Link, Opens in New Window

Deployment Cycle Support (http://www.pdhealth.mil/dcs/default.asp) External Link, Opens in New Window

Veterans Affairs External Link, Opens in New Window

National Institute of Mental Health External Link, Opens in New Window

Tricare® External Link, Opens in New Window

Military Oncesource (http://www.militaryonesource.com/skins/MOS/home.aspx) External Link, Opens in New Window

Post Traumatic Stress Disorder (PTSD) Manual External Link, Opens in New Window

US Army Public Health Command External Link, Opens in New Window

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DoD Directive 6490.1 Mental Health Evaluation
DoD Directive 6490.5 Combat Stress Control (CSC) Programs
DOD/ VA guidelines for COSR External Link, Opens in New Window
FM 4-02.51, Combat and Operational Stress Control (replaces FM 8-51, SEP 94)
FM 6-22.5, A Leader's Guide to Combat and Operational Stress (Replaces FM 6-22.5, COSC, JUN 00 and FM 22-51, LEADERS' MANUAL FOR COMBAT STRESS CONTROL, SEP 94)
MEDCOM 40-38, Command Directed Mental Health Evaluations, SEP 01

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Key Terms

Active Listening:

Active, effective listening is the foundation of effective communication.  Active listening intentionally focuses on who you are listening to in order to understand what he or she is saying.  As the listener, you should then be able to repeat back in your own words what they have said to their satisfaction.  You do not have to agree with, like, or fix the problems that you are hearing.  Your job is simply to convince the other person that you understand what they're trying to say.  A good web site on this technique can be found at: http://www.taft.cc.ca.us/lrc/class/assignments/actlisten.html External Link, Opens in New Window

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Behavioral Health Assets:

Behavioral health sections are assigned to brigades, divisions, corps, and theater-level medical units.  The BH section coordinates, supervises and provides the primary COSC functions through a vigorous prevention, consultation, training, educational, and Soldier restoration programs.  These programs are designed to provide COSC expertise to unit leaders and Soldiers where they serve to sustain their mission focus and effectiveness under heavy and prolonged stress.

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Provides spiritual guidance, personal counseling, and life issues counseling in a confidential setting.  Chaplains are protected by the Uniform Code of Military Justice, which ensures confidentiality.  Under military law, chaplains must keep conversations confidential when service members seek their spiritual guidance, either as a formal act of religion or a matter of conscience.  Chaplains do not have to keep conversations confidential when a service member speaks with them for reasons other than spiritual guidance.  When it is in the best interest of the person involved, the chaplain is expected to assist the individual in identifying the appropriate means of self-disclosure without violating the individual's trust.

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COSC Team:

The mission of the echelon above division (EAD) COSC team is to provide COSC interventions and stress prevention activities to supported units in its AO.  The team augments organic division and brigade BH sections; provides direct support to combat brigades without organic BH officers; and provides area support in its AO.  The COSC team reconstitutes other brigade and division COSC assets.  Depending on mission and theater objectives the team may provide COSC activities to indigenous populations.  These activities are command directed in stability operations, humanitarian assistance, disaster relief, peace support operations, and detention facility operations.  It also provides COSC interventions and activities to units in support of their readiness preparation and throughout their deployment cycle.

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Command Directed Evaluation (CDE):

In accordance with (IAW) DODD 6490.1, commanding officers (CO) may direct Soldiers to undergo a MH evaluation.  A CDE is appropriate whenever the CO believes that the Soldier's mental state renders them a risk to themselves or others or may be affecting their ability to carry out the mission.  A CDE can provide the CO with information needed to make an appropriate administrative action.

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Deliberately faking symptoms of a disorder, including suicidal thoughts, personality disorder, etc, for secondary gain, such as getting out of military service obligations.

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Military OneSource:

The services of Military OneSource supplement the existing support system for Soldiers and their families by providing assistance 24 hours a day, 7 days a week via toll free telephone and Internet access.  In addition, Military OneSource supports geographically dispersed Soldiers and their families (recruiters, Inspector and Instructor staffs, and mobilized reservists) who do not have traditional services available.  Resources are available on topics to include parenting and childcare issues, education services, financial information and counseling, legal, elder care, health and wellness, crisis support and relocation.  Soldiers or family members seeking assistance can call 800-342-9647.  Military OneSource Online can be visited at www.militaryonesource.com.

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Post Traumatic Stress Disorder (PTSD):

A psychiatric illness characterized by chronic intrusive recollections, emotional numbing, and hyper-alertness associated with a prior traumatic experience.  A related condition, Acute Stress Disorder, is psychiatric illness characterized by immediate, severe response to a traumatic incident—usually involving significant dissociation or mental "disconnection" from the person's surroundings.  These conditions are relatively uncommon, and only a subset of those exposed to a traumatic situation will go on to develop PTSD or other psychiatric conditions such as clinical depression.  The rest of those individuals who undergo a difficult experience such as combat are likely to experience some short-term emotional response.  This is normal and is, in fact, valuable: increased alertness and decreased sleepiness, for example, are useful short-term responses to danger.  When these reactions persist after the danger is passed, they are referred to as "combat and operational stress reactions"—a normal response to an abnormal situation.  It encompasses reactions not only to combat, but also other challenging experiences encountered working in an operational environment.

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Posttraumatic Growth (PTG):

A phenomenon in which positive outcomes occur among survivors of a wide range of traumatic experiences, such as car accidents, fires, sexual abuse/assault, military combat, and being held as a refugee.  Posttraumatic growth among trauma survivors has included improved relationships, renewed hope for life, an improved appreciation of life, an enhanced sense of personal strength, and spiritual development.

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Potentially Traumatizing Event (PTE):

An event is considered a potentially traumatizing event when it causes individual Soldiers or even a whole unit to experience intense feelings of terror, horror, helplessness, and/or hopelessness.  Guilt, anger, sadness, and dislocation of world view or faith are potential emotional/cognitive responses to PTEs.

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Traumatic Event Management (TEM):

Traumatic Event Management is the term utilized by the U.S. Army referencing interventions and support activities in response to potentially traumatizing events (PTE) that occur individually or organizationally to units and organizations.  It is a flexible set of interventions specifically focused on stress management for units and individual Soldiers.

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