A diplomatic conference leading to the Convention on Cluster Munitions (CoCM) was held on 30 May 2008 with the aim of banning the use of cluster munitions for all countries that ratified the Convention. Currently, 111 states are parties to the Convention and 12 are signatories. Despite the high number of participants in the treaty, success remains relative as some key major powers including the United States and Russia are missing. Furthermore, there is an important nuance reflected in the treaty concluded in Article 21, which explains that parties to the treaty are allowed to cooperate militarily with states that do use these weapons that are prohibited by the Convention (Convention on Cluster Munitions, 2008). Why is there controversy regarding the use of cluster munition and what are the consequences of Article 21 CoCM?