This report is the result of a series of brainstorming sessions that took place between the summer of 2013 and the winter of 2014-2015, and between American, Russian, and European experts. The teams were led by Ellen Tauscher, the Vice Chair of the Atlantic Council's Brent Scowcroft Center on International Security and the former US Under Secretary of State for Arms Control and International Security, and Igor Ivanov, the president of Russian International Affairs Council (RIAC) and former Foreign Minister of Russia, in an effort to keep the dialogue open and frank at a challenging time for European security. Not surprisingly, as events in Ukraine unravelled the post-Cold War security order, it proved impossible to narrow the differences and develop a common, action-oriented approach to the challenge of rebuilding the European security order.