John J. Mearsheimer, the R. Wendell Harrison Distinguished Service Professor in Political Science and Co-director of the Program on International Security Policy at the University of Chicago, assesses the causes of the present Ukraine crisis, the best way to end it, and its consequences for all of the main actors. A key assumption is that in order to come up with the optimum plan for ending the crisis, it is essential to know what caused the crisis. Regarding the all-important question of causes, the key issue is whether Russia or the West bears primary responsibility.