Historian, professor emeritus at the Sorbonne, member of the Académie des sciences morales et politiques, president of the Institut de stratégie comparée. His fields of research are related to international relations in the twentieth century, particularly on the First World War and East-West relations after 1945. His latest works: La Guerre froide de la France, 1941-1990, Paris, Tallandier, 2018; La Grande Illusion. Quand la France perdait la paix, 1914-1920, Paris, Tallandier, 2015.