The Introduction poses the question of how we should best understand the military conflict that began in 2014, showing why the prevailing explanations are insufficient. After the collapse of the Soviet Union, many analysts believed that the problems of security in central Europe had disappeared. Security challenges did not disappear in 1991 and resurface later, but rather persisted. This chapter uses three concepts in international relations theory – the security dilemma, loss aversion, and the democratic peace – that will be used throughout the book to show why the new conflicts could not easily be managed.