Since 1997, NATO, the world’s most powerful military alliance, has created more insecurity than security. This book, a bestseller in German by one of Europe’s most important left politicians, shows how. NATO is in decline. It is threatened with a disaster which is even worse than the lost war in Afghanistan. Despite all its talk of an impending victory, the alliance is winning neither the proxy war in Ukraine nor the economic war against Russia. Instead of following NATO in its course of further escalation which is driving humanity down towards the abyss, we should use the current existential crisis of the military alliance to work for a real system of collective security which is not directed against an external enemy but tries to work for peace internally. The search for alternatives to NATO is part of the resistance to a policy that leads to a world war. We need peace, not NATO. Sevim Dagdelen provides a much-needed reckoning with NATO on its 75th anniversary. She stresses the importance of alternative narratives and actions as well as new ideas for a 21st-century security architecture.