Former Defense Secretary Donald Rumsfeld is remembered for many things, among them his iconic observation that, "There are known knowns--there are things we know we know. We also know there are known unknowns--that is to say, we know there are some things we do not know. But there are also unknown unknowns, the ones we don't know we don't know." The ongoing Russian invasion of Ukraine is full of reminders of the importance of understanding what we know, recognizing what we don't know, and being open to the idea that there is likely more we don't yet know. In order to help make sense of it, the Clements Center for National Security, Asia Policy Program, LBJ School of Public Affairs, Strauss Center for International Security and Law, Intelligence Studies Project, and Center for Russian, East European and Eurasian Studies at the University of Texas, Austin hosted "War in Ukraine: An Expert Panel Discussion" on Wednesday, March 2. The experts included Will Inboden, executive director of the Clements Center (and editor-in-chief of TNSR); Bobby Chesney, director of the Strauss Center; Jeremi Suri, Mack Brown Distinguished Chair for Leadership in Global Affairs at the University of Texas, Austin; Sheena Greitens, founding director of the Asia Policy Program; Stephen Slick, director of the Intelligence Studies Project; Alexandra Sukalo, postdoctoral fellow at the Clements Center; and, Zoltán Fehér, predoctoral fellow at the Clements Center, and a former Hungarian diplomat. This discussion is essential listening for a better understanding of the ongoing aggressive war being waged by Russia and its implications for international security.