Background:
Republic of Korea has an obligatory military service. All Korean men in their 20s are obliged to serve the military for 21 months. The purpose of this study was to identify smoking prevalence among the Korean military and to understand how the soldiers change their smoking behavior during their obligated military service.

Methods:
A tobacco use survey for the military was carried out by the Korean Association of Health Promotion on behalf of the Ministry of Health in July, 2016. The participants were asked to answer the questions regarding current and past experience of tobacco use, their smoking behavior change during the military service.

Results:
The total number of participants in the survey were 3,800 soldiers. Among them, 44.9% (1,707 soldiers) of the participants were current smokers. Marine Corps had the highest smoking prevalence with 51.7%, following Army with 48.5%, Navy with 39.1% and Air force with 32.7%. The branches of the military were associated with soldiers' smoking prevalence (p< .001). There were 726 participants (63.5%) who answered that their smoking frequency has increased in the military service. The reasons being; tough training or stress of the military life (72.6%, 527 soldiers). In addition, the participants answered that in order to have a break, they smoked more often. There was a large group of dual users (34.9%) between cigarettes and electronic cigarettes. The rank was associated with dual use of cigarettes and electronic cigarettes (p=.007).

Conclusions:
The smoking prevalence among soldiers were higher compared to that of the same age group in the population. The military life has affected the young soldiers' smoking behavior. Effective tobacco control intervention should be employed in the military and this will contribute to the decrease in the smoking prevalence among Korean males.