The beginning of the second decade of the new millennium was marked by many events which need global action. All challenging events open dilemma Do the current principle of Collective Security provides rationality to uphold international peace and stability.There are some frozen conflicts at the Europe continent, which might be a security issue for peace and security in the Euro-Atlantic area. Security dilemmas associated by: the achievement of a lasting of peace in the Middle East, stopping Iran's nuclear ambitions, growing Islamic radical fundamentalism, Crimea s annexation, challenging NATO and EU integration of Western Balkans countries, remains a major challenge around which powerful countries "fought" for domination.This paper reflects on these fundamental questions through an analysis of collective security principles as well as implications of the new security dilemmas. It focuses on exploring the logic and utility of Russia s proposed European Security Treaty and connection with Crimea s annexation, as well as Western respond to this demonstration of Russian s power. This book is for political and security experts who research actual security challenges and dilemmas.