When the UN Security Council (the Council) authorises military action under Chapter VII of the Charter, question marks arise concerning the legality and purpose of such operations. The contents of Chapter VII of the Charter are not literally being complied with, and States contributing to the force can be accused of using force in pursuit of their own national interests as opposed to the collective interests of the UN. When a State, or a group of States is authorised to use force to combat aggression, as against North Korea and Iraq, or to deal with threats to the peace, as in Somalia, Rwanda, Haiti, Bosnia, Zaire and Albania, there is also confusion as to whether the States in question are simply exercising their inherent rights of self-defence, or are operating under the cloak of the controversial doctrine of humanitarian intervention with the encouragement of the Council, or whether these are UN military operations somehow distinct from the forces of blue helmets that the UN is more famous for. Such confusion is further compounded by the new functions of the military option in the post-Cold War era. The collective security system that has evolved in practice is inevitable in a world where powerful States jealously harbour their military strength, thereby only allowing its collective use within a system that respects their interests. However, despite clear deficiencies, it is the contention here that UN-authorised actions are collective enforcement operations with a sound constitutional basis in the UN Charter. Internal regulation of such operations is ensuring UN control and a system of accountability to the Council. Practice shows that States regard these operations as serving the UN's purposes and not simply promoting national interests. This can only prove to strengthen the decentralised system and legitimise military action.