Abstract: Recent advances in artificial intelligence (AI) created powerful tools for research, particularly for extracting meaningful insights from extremely large data sets. These developments increase research benefits of big data and risks posed to individual privacy, forcing a re-examination of ethics in research which is of particular importance to the Military Health System. To advance discussion of research ethics in this context, the Forum on Health and National Security: Ethical Use of Big Data for Healthy Communities and a Strong Nation was held in December 2018. The workshop was designed to identify ethical questions relevant to population and health research studies using difficult to access, health-related data in the Department of Defense (DoD). Discussions explored researchers’ ethical obligations to research subjects, particularly in the areas of privacy, trust, and consent, as well as potential methods to improve researchers’ ability to collect, access, and share data while protecting privacy and potential risks to national security. These include creating risk management frameworks and data governance policies, improving education and workplace training, and increasing community involvement in research design and practice. While the workshop was conducted in 2018, the discussion of data ethics is still relevant today. The research agenda of the nation is best served by building ethics into the research ecosystem. There are substantial challenges to fully realizing this goal including commitments of time and funding to address the ethical complexities, train others to understand them, and create appropriate ethical frameworks before research begins.