The Organisation for Joint Armament Cooperation (Organisation Conjointe de Coopération en matière d'Armement / OCCAR) was initially established by an Administrative Arrangement signed by the Defence Ministers of France, Germany, Italy and the UK on 12th November 1996. The aim of OCCAR is to increase the armaments cooperation of the Member States in order to improve efficiency and reduce costs.
In 1998, the Defence Ministers of the four founding Member States signed the treaty-like "OCCAR Convention", which was subsequently ratified by the national Parliaments and came into force on 28th January 2001. The Convention gives OCCAR its legal status, allowing it to award contracts and to employ its own staff. Belgium and Spain joined OCCAR respectively in 2003 and 2005.