Tobacco-related deaths exceed those resulting from homicides, suicides, motor vehicle accidence, alcohol consumption, illicit substance use, and acquired immunodeficiency syndrome (AIDS), combined. Amongst U.S. veterans, this trend is particularly concerning given that those suffering from posttraumatic stress disorder (PTSD)-about 11% of those receiving care from the Department of Veterans Affairs (VA)-have triple the risk of developing tobacco use disorder (TUD). The most efficacious strategies being used at the VA for smoking cessation only result in a 23% abstinence rate, and veterans with PTSD only achieve a 4.5% abstinence rate. Therefore, there is a critical need to develop more effective treatments for smoking cessation. Recent studies have revealed the insula as integrally involved in the neurocircuitry of TUD, specifically showing that individuals with brain lesions involving this region had drastically improved quit rates. Some of these studies show a probability of quitting up to 5 times greater compared to non-insula lesioned regions). Altered activity of the insula may be involved in the disruption of the salience network's (SN) connectivity to the executive control network (ECN), which compromises that patient's ability to switch between interoceptive states focused on cravings to executive and cognitive control. Thus, we propose a feasibility phase II randomized controlled trial (RCT) to study a patterned form of repetitive transcranial magnetic stimulation (rTMS), intermittent theta burst stimulation (iTBS), at 90% of the subject's resting motor threshold (rMT) applied over a region in the right post-central gyrus most functionally connected to the right posterior insula. We hypothesize that by increasing functional connectivity between the SN with the ECN to enhance executive control and by decreasing connectivity with the default mode network (DMN) to reduce interoceptive focus on withdrawal symptoms, we will improve smoking cessation outcomes. Fifty eligible veterans with comorbid TUD and PTSD will be randomly assigned to two conditions: active-iTBS + cognitive behavioral therapy (CBT) + nicotine replacement therapy (NRT) (n=25) or sham-iTBS + CBT + NRT (n=25). The primary outcome, feasibility, will be determined by achieving a recruitment of 50 participants and retention rate of 80%. The success of iTBS will be evaluated through self-reported nicotine use, cravings, withdrawal symptoms, and abstinence following quit date (confirmed by bioverification) along with evaluation for target engagement through neuroimaging changes, specifically connectivity differences between the insula and other regions of interest.