Article J.7 of the Amsterdam Treaty, which amends the treaty on European Union, establishes that the Western European Union shall provide the European Union with access to an operational capability for “humanitarian and rescue tasks, peacekeeping tasks, and tasks of combat forces in crisis management, including peacekeeping.” Making reference to 1992 WEU Petersberg Declaration, these tasks are commonly known as Petersberg operations. This provision constitutes the integration of a part of the “WEU acquis” into the framework of the European Union, even though there is no institutional integration between the two organizations or legal interweave between their constituents treaties. The decision-making mechanism for Petersberg operations must be considered in relation to the new CFSP set of acts and it involves considerable interplay between the European Council, the Council and the WEU Council of Ministers. Several problems might arise from the different voting systems of these institutions and a specific question is posed by the more restricted composition of the WEU with respect to the EU, namely the five EU member States which are not fully-fledged WEU members. The development of an EU crisis management capability could have several positive consequences, both on an inter-European level and externally.