The efforts to define the crime of aggression as an international crime are accompanied by many problems. Some countries see it as a sign of salvation against foreign interference in internal affairs, while others see it as a limiting factor in achieving their own interests. In the battle between consensus and contestation every victory was a Pyrrhic one and the price of any compromise was high. However, after the Review Conference of the Rome Statute of the International Criminal Court, which was held in 2010, we have many reasons for optimism. In this paper, the author presents the historical development of the crime of aggression from the theoretical discussion to its criminalization as an international crime. It is through a critical analysis of the norms in international documents and judgments of international courts based on them that we point to all the advantages and disadvantages of defining aggression. In his conclusion, the author predicts the future of the crime of aggression, bearing in mind the latest solutions in theory and practice of international criminal law.