In 2003, when the EU adopted its first European Security Strategy, Europe saw itself as at peace, secure, and prosperous. This feeling of security in Europe was challenged at different times by different actors, but the last blow came with the ongoing Russia-Ukraine war. After almost three years of war in Ukraine, the issue of deterrence has gained utmost importance in Europe in the face of the Russian challenge. This chapter tries to understand how deterrence works for Europe and how forward presence and forward defense becomes part of deterrence logic in the European security architecture. As has been stated in many NATO documents, deterrence is the heart of the Alliance’s security. However, because of the risk of escalation embedded in the nature of the Russia-Ukraine war as well as the fear of abandonment by the US, European actors have to answer the question of the major impediments they need to overcome in terms of ensuring their security by their own means. This chapter will also try to clarify what the Europeans can do in this regard, and whether European deterrence can be an answer.