MATERIALS AND METHODS: We searched for published English articles in Medline, Web of Science, Scopus, and Google Scholar databases using relevant subject headings without year restriction. We included randomized controlled trials, nonrandomized controlled trials, case-control, cohort, controlled before and after, and uncontrolled before and after studies evaluating the impact of tobacco control policy in the military population. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, three independent reviewers independently screened initially identified articles, reviewed the full text, and extracted the data and any disagreements resolved by consensus after data recheck. Five reviewers used a validated tool to assess the quality of the included studies. The primary outcome was the reduction of any tobacco or nicotine-contained products (TNCPs) use among the troops. The impacts of the tobacco control policy were synthesized and analyzed qualitatively. This study is registered with the International Prospective Register of Systematic Review (CRD42022314117).

RESULTS: Fourteen studies were included in the analysis from 5372 studies screened. Most of the studies were from the USA, and fractions were from Thailand, France, and Taiwan. These studies were methodologically heterogeneous. Most studies employed a total ban policy on TNCP use during basic military training or operational deployment as the primary strategy. Other methods utilized were the brief tobacco intervention, targeted treatment, support, and counseling provided through telephone or mailing systems, the adjunctive behavioral intervention, providing free nicotine gum, the "Pharsai clinic", active and regular smoking restriction, and interventions aimed at intrapersonal, interpersonal, and organizational levels. There is a moderate quality of evidence that the tobacco control policies effectively reduced the prevalence of TNCP use, increased the cessation rate, reduced the intake, and lowered the dependency. The adjunctive interventions provided after the total ban on TNCP use may increase its effectiveness. However, findings from this review need to be carefully considered as the definition of TNCP use status was not universal between studies and lacked a biochemical validation procedure.