A United States ambassador said Thursday Washington was concerned at the possibility of aggression being designated an international crime. 'I would be remiss not to share with you my country's concerns about an issue pending before this body, to which we attach particular importance: the definition of the crime of aggression,' US war crimes ambassador Stephen Rapp told a gathering in The Hague of the International Criminal Court's Assembly of State Parties (ASP). According to the court's founding Rome Statute, of which the United States is not a signatory, the ICC can try the crime of aggression, but no legal definition has yet been agreed upon. The issue is due to be discussed at an ICC review conference in Kampala, Uganda, in May next year. Rapp said Washington was concerned about the way a draft definition of aggression has been framed. 'Our view has been and remains that, should the Rome Statute be amended to include a defined crime of aggression, jurisdiction should follow a Security Council determination that aggression has occurred.' He declined to elaborate when approached afterwards. The United States is taking part in a meeting of the ASP, as an observer, for the first time since the court started operating in 2002. 