in units in reserve positions, logistical units or at medical companies. every effort is made to reinforce service members' identity. they are required to wear their uniforms and to keep their helmets, equipment, chemical protective gear, and flak jackets with them. when possible, they are allowed to keep their weapons after the weapons have been cleared. they may serve on guard duty or as members of a standby quick reaction force. screening historically, screening programs that have attempted to preclude soldiers exhibiting personality traits thought to predispose them to csr have been a total failure. part of this failure stems from the inability to base csr morbidity on one or two personality traits. full psychological work-ups are expensive and inconclusive, while pen and paper tests are ineffective and easily faked. in addition, studies conducted following wwii screening programs showed that psychological disorders present during military training did not accurately predict stress disorders during combat. cohesion while it is difficult to measure the effectiveness of such a subjective term, soldiers who reported in a wwii study that they had a "higher than average" sense of camaraderie and pride in their unit were more likely to report themselves ready for combat and less likely to develop csr or other stress disorders. soldiers with a "lower than average" sense of cohesion with their unit were more susceptible to stress illness. training stress exposure training or set is a common component of most modern military training. there are three steps to an effective stress exposure program. providing knowledge of the stress environment soldiers with a knowledge of both the emotional and physical signs and symptoms of csr are much less likely to have a critical event that reduces them below fighting capability. instrumental information, such as breathing exercises that can reduce stress and suggestions not to look at the faces of enemy dead, is also effective at reducing the chance of a breakdown. skills acquisition cognitive control strategies can be taught to soldiers to help them recognize stressful and situationally detrimental thoughts and repress those thoughts in combat situations. such skills have been shown to reduce anxiety and improve task performance. confidence building through application and practice soldiers who feel confident in their own abilities and those of their squad are far less likely to develop combat stress reaction. training in stressful conditions that mimic those of an actual combat situation builds confidence in the abilities of themselves and the squad. as this training can actually induce some of the stress symptoms it seeks to prevent, stress levels should be increased incrementally as to allow the soldiers time to adapt. prognosis figures from the 1982 lebanon war showed that with proximal treatment, 90% of csr casualties returned to their unit, usually within 72 hours. with rearward treatment, only 40% returned to their unit. it was also found that treatment efficacy went up with the application of a variety of front line treatment principles versus just one treatment. in korea, similar statistics were seen, with 85% of us battle fatigue casualties returned to duty within three days and 10% returned to limited duties after several weeks. though these numbers seem to promote the claims that proximal pie or biceps treatment is generally effective at reducing the effects of combat stress reaction, other data suggests that long term ptsd effects may result from the hasty return of affected individuals to combat. both pie and biceps are meant to return as many soldiers as possible to combat, and may actually have adverse effects on the long-term health of service members who are rapidly returned to the front-line after combat stress control treatment. although the pie principles were used extensively in the vietnam war, the post traumatic stress disorder lifetime rate for vietnam veterans was 30% in a 1989 us study and 21% in a 1996 australian study. in a study of israeli veterans of the 1973 yom kippur war, 37% of veterans diagnosed with csr during combat were later diagnosed with ptsd, compared with 14% of control veterans. controversy there is significant controversy with the pie and biceps principles. throughout a number of wars, but notably during the vietnam war, there has been a conflict among doctors about sending distressed soldiers back to combat. during the vietnam war this reached a peak with much discussion about the ethics of this process. proponents of the pie and biceps principles argue that it leads to a reduction of long-term disability but opponents argue that combat stress reactions lead to long-term problems such as post-traumatic stress disorder. the use of psychiatric drugs to treat people with csr has also attracted criticism, as some military psychiatrists have come to question the efficacy of such drugs on the long-term health of veterans. concerns have been expressed as to the effect of pharmaceutical treatment on an already elevated substance abuse rate among former people with csr. recent research has caused an increasing number of scientists to believe that there may be a physical (i.e., neurocerebral damage) rather than psychological basis for blast trauma. as traumatic brain injury and combat stress reaction have very different causes yet result in similar neurologic symptoms, researchers emphasize the need for greater diagnostic care.