Participation in the International Military Operations (IMO) in a foreign country means separation from family, increased physical activities, changes of living and working habits, new duty of responsibilities and permanent tension. The purpose of this study was to explore stress factors encountered in peacekeeping mission in Afghanistan, the nature of feelings across operational phases of deployment, and positive aspects of deployment. The data were collected with questionnaire constructed for this research. Research is conducted on a sample of 180 soldiers, three months post-deployment. Findings suggest that there are a wide range of stressors in the missions; most common are unfamiliar cultural and climate surrounding, possibility of hazardous illness, language barrier, separation from family and concerns about family welfare. Furthermore, degree of stress experienced during deployment is medium intensity. The results indicates that a nature of feelings varies across operational phases; excitement in the beginning of deployment, increased self-confidence and self-competence in the middle and feelings of happiness and proud at the end of deployment. Present study has shown that, although participation in international military operation is characterized with great deal of stress factors; many peacekeeper soldiers perceive lots of positive aspects. These results provide useful information and leads to recommendations for training and psychological preparation of soldiers preparing for deployment.