Mark Greaney has a degree in international relations and political science. He is the author of the New York Times bestsellers Tom Clancy Support and Defend, Tom Clancy Full Force and Effect, Tom Clancy Commander in Chief, and Tom Clancy True Faith and Allegiance. With Tom Clancy he coauthored Locked On, Threat Vector, and Command Authority. He has written six books in his own Gray Man series: Gunmetal Gray, Back Blast, Dead Eye, Ballistic, On Target, and The Gray Man. In his research for these novels, he traveled to fifteen countries, and trained alongside military and law enforcement in the use of firearms, battlefield medicine, and close-range combat tactics.