With this research investigators hope to begin to understand how rTMS can improve posttraumatic stress disorder (PTSD) symptoms. TMS improves PTSD through two interrelated mechanisms: change in brain limbic system function and change in systemic inflammatory activation. Participants who decide to join this study, will receive ten rTMS treatments. All participants will undergo a 40-minute rTMS procedure with a member of the study team 10 times over 2-4 weeks. Participants will undergo fMRI scans of the head in order to help researchers better understand potential effects of rTMS on brain activity. In addition, participants will be asked to give two breath and blood samples to look for signs of general inflammation.

Inclusion Criteria:

• Age between 19 and 70
• Eligible for VA healthcare
• Moderate to severe PTSD as determined by a total score of at least 25 on the CAPS within 7 days of randomization.
• Agree to have CAPS audio recorded.
• Ability to obtain a Motor Threshold using the TMS device during screening.
• If female with childbearing potential, use of acceptable method of birth control (i.e., use of contraceptives, abstinence).
• Able to read, understand, and sign the informed consent document.

Exclusion Criteria:

• Pregnant or lactating woman.
• MRI is contraindicated
• Current use of clozapine (any dose) or bupropion (more than 300mg per day).
• Cardiac pacemaker or implantable defibrillator.
• Presence of any metal object in the head, including cochlear implants, but excluding dental work in the mouth.
• Significant central nervous system disorder (stroke, brain mass, epilepsy).
• Seizure in past one year.
• Current psychosis or mania.
• Significant suicidal ideation.
• Unstable medical conditions.
• Current alcohol or substance use disorder (except nicotine) that interferes with the patient's ability to participate.
• CPT or PE for PTSD in the past 2 months.
• Changes in Fluoxetine, Paroxetine, Sertraline, or Venlafaxine in the past 2 months.
• Color blind
• Currently participating in other research studies.
• Aneurysm Clip
• Ocular foreign body (e.g., metal shavings)
• Any implanted device (pumps, infusion devices, etc.)
• Shrapnel injuries or metal fragments