Her areas of expertise include defense strategy, posture, force planning, the defense budget, airpower, and wargaming. Her current projects focus on the effect of drones on warfare, munitions stockpiles, and nuclear deterrence in a multipolar world. Pettyjohn also serves as the Chair for Total Force Integration Subcommittee on the Reserve Forces Policy Board, a federal advisory committee within the Office of the Secretary of Defense and teaches a graduate course on wargaming as an adjunct professor at Johns Hopkins School of Advanced and International Studies (SAIS).