In the spirit of Jean Monnet's desire to "Continue, continue, there is no future for the people of Europe other than in union", this volume analyses the process of European construction, paving a road to the United States of Europe. It focuses on the challenges and issues the Union is currently facing, from illegal migration, to the refugee crisis, fake news, populism, insecurity, the Eastern Partnership, and the COVID-19 pandemic. For the European Union's citizens, security was, is, and will remain a top priority. The book is part of a constructivist approach with a dynamic perspective on the political, social, economic, military and societal, where the actors and the system structure are interconnected. It will appeal to students, professors, researchers, stakeholders, politicians, and specialists on international relations and security studies, as well as the general public interested in the evolution of the European Union, today's challenges and tomorrow's opportunities.