Co-operation has proved to be one of the greatest challenges in the first practice of the International Criminal Court (ICC). The Court cannot fulfil its mandate effectively without co-operation from states, international organizations, and other actors. The Prosecutor requires co-operation and assistance at various stages of proceedings (preliminary examination, investigation, judicial proceedings) in order to conduct investigations and prosecutions. The Court depends on the co-operation of states to execute the warrants of arrest and proceed to trial. In the context of its first practice, the Court has operated in situations of ongoing conflict and/or environments where the security situation is volatile. The level and modalities of co-operation were influenced by the factual and political conditions on the ground and the institutional support of other entities (e.g. the United Nations).