His research investigates strategy and statecraft on the brink of war. Much of it focuses on two important-yet-neglected tools of statecraft: the red line and the fait accompli. He is developing a book manuscript, Red Lines in International Politics, that explores how and why some red lines effectively constrain behavior while others do not. It emphasizes the strategies states use to erode and circumvent red lines without provoking war. To study the fait accompli, he created a dataset of all “land grabs” since 1918, with Crimea the most recent. More recently, he expanded it into the Modern Conquest dataset, the most comprehensive data on territorial conquest back to 1918. That lays the groundwork for a revised history of territorial conquest and territorial war in the modern era. He has an enduring research interest in the causes of war.