Syria's bloody civil war has plunged the cradle of the Levant into a painful spiral of violence. This spiral of violence has caused profound social, political, economic, and strategic changes in Syria. But the effects of the civil war are not limited to Syria. The civil war in Syria has become a direct problem not only for Syria but also for Türkiye, Iraq, Lebanon, and Jordan. However, most observers agree that of all Syria's neighbors, Türkiye has been the most affected by the civil war.When one thinks of Türkiye and Syria together in recent years, two concepts come to mind most often: Military operations and migration. However, conflicts in Syria have been perceived in a broader security paradigm in Türkiye.The main topics of the book can be summarized as follows: Border issues, sovereignty disputes, alliances, and military interventions in Türkiye-Syria relations. The effects of the civil war in Syria on Türkiye's foreign policy, economy, social structure, and internal security. Reflections of the civil war on Türkiye's relations with Iran, the US, and Russia. Increasing separatist and radical Salafist terrorism in Türkiye in line with the spillover effect of civil wars. Cross-border operations and Türkiye's military capacity. The problem of migration. Within the framework of the topics addressed, the book provides a comprehensive reading of the security problems caused by the Syrian Civil War on Türkiye. We believe that this book will shed light on why Türkiye perceives what is happening in Syria from a security perspective. In fact, the main idea of the book is simple: Syria has been a security issue for Türkiye since the 1930s, and it is still a security issue now. After approximately 100 years, the main idea has not changed. The only thing that has changed is how security is defined.