This book explores whether the United Nations (UN) is relevant in resolving wars when the permanent members of the UN Security Council are directly or indirectly involved. It examines solutions to major wars by applying and testing the UN’s vast experience in mediating and deploying peacekeeping, demilitarization, truce monitoring, UN temporary administration, and other tools. While some observers see the organization in deep decline as the Security Council cannot agree to stop the wars in Ukraine and Gaza, the expert contributors to this volume make the case that until the start of this century the UN played a critically important role in resolving and freezing major conflicts, and the renewal of the organization could be based on these and other successful precedents. This volume will be of interest to scholars and students of global governance, security studies, and the history of the UN in the maintenance of international peace and security. It will also be of great interest to practitioners at the UN and its partner organizations as well as to diplomats around the world.