Since the publication of the first edition of International Law and the Use of Force, events have led to a major reappraisal of international law on the use of force. The terrorist attacks of September 11th and Operation Enduring Freedom in Afghanistan have raised fundamental questions about the right to use force in self-defense against terrorism, and the scope of the 'war on terror'. The question of whether there is now a new doctrine of pre-emptive self-defense has divided States. The invasion of Iraq in 2003 has prompted serious questions about the role of the United Nations and the legal basis of Operation Iraqi Freedom: had the UN Security Council authorized the use of force against Iraq? Was the US entitled to act without such authorization? This volume covers the whole of the large and controversial subject of the use of force in international law; it examines not only the use of force by States, but also the role of the UN and regional organizations in the maintenance of international peace and security.