What would happen if the nuclear balance were to be upset? To what extent do we live under the threat of an atomic catastrophe? Could Europe become the epicenter of a new global crisis? Nuclear weapons have shaped the history of international relations since their appearance. They have been the greatest guarantee of deterrence, but also the shadow that threatens world peace. Today, in a context of growing geopolitical tensions, Europe's security is once again in question. Lieutenant General (R) Eduardo Zamarripa offers us in this book an enlightening journey through the evolution of nuclear weapons, from their development in World War II to their role in the Cold War and disarmament treaties. With a rigorous but accessible approach, he analyzes the role of European nuclear powers such as France and the United Kingdom, reveals the moments when Spain came closest to possessing its own atomic bomb, and examines the dangerous resurgence of the nuclear threat in current conflicts such as the one in Ukraine. More than a historical analysis, this book is a call to reflection: Are we prepared for a new nuclear crisis? Can international agreements stop an arms race? Is a future without the shadow of atomic destruction possible? An essential essay for understanding the security challenges that will shape Europe's destiny in the 21st century.