The defining moments of 2001, the terrorist attacks of September 11 against the UnitedStatesofAmerica, markedaturningpointininternational lawandrelations. Bytheirscaleandaudaciousness, overnighttheyhelpedtopropeltheissueofint- national terrorism to the top of the international security agenda and particularly that of the USA, with consequences for many branches of international law, including the jus ad bellum, the jus in bello, international law relating to terrorism, international human rights law and international criminal law, that were just beginning to be felt as the year closed. The September 11 attacks were immediately characterised by the United States 3 as an act of war, an armed attack on such ascale asto constitute an armed conflict. Its immediate response was to declare a so-called 'Global War on Terrorism'. Avowedly acting in self-defense, on 7 October the US launched armed attacks against Afghanistan, notbecause Afghanistan wasconsidered tobelegally resp- sible for the September 11 attacks but for harbouring and refusing to surrender members of Al Qaeda, including its leader, Osama Bin Laden, and refusing to dismantle terrorist training camps. Although the main target of the attacks was Al Qaeda, the armed conflict that ensued was an international armed conflict between the US and its allies and the state of Afghanistan, notwithstanding that the US never recognised the Taleban as the government of Afghanistan.

3 On 22 February 2002, Jonas Malheiro Savimbi, who led the UNITA rebel move- 4 ment during the bloody armed conflict in Angola and who had battled to take power by force since Angola's independence from Portugal in 1975, was killed in 5 a gun battle with the Angolan Army. During the Cold War, Savimbi was a proxy for the United States against the then-Marxist government of Angola. But after the end of the Cold War, he lost international support for rejecting peace efforts. He was accused of perpetuating a bloody internal conflict to advance his own interests 6 and was exposed to international sanctions. Meanwhile, the government of Presi- 7 dent Jose Eduardo dos Santos moved closer to the United States. The 27-year-long armed conflict is believed to have killed approximately one million people and driven four million others from their homes, creating a humani- 8 tarian crisis. In addition, the conflict destroyed almost all of the country's inf- structure, and effectively disrupted every effort by the government to start the long desired national reconstruction after independence, and the building of prosperity for the nation's children. Savimbi was viewed as the primary obstacle to peace, personifying the 'corrupt- 9 ing influence of ambition, mineral wealth, and the grinding brutality of war'. His 3. 'UNITA' is the Portuguese acronym for 'National Union for the Total Independence of Angola' (Uniao Nacional para a Independencia Total de Angola). It was founded in 1966 by the late Mr Jonas Savimbi."

In 2004, the Report of the Secretary-General's High-Level Panel on Threats, Challenges and Change emphasised the linkages between economic development, security and human rights, and the imperative in the twenty-first century of collective action and cooperation between States. In a world deeply divided by differences of power, wealth, culture and ideology, central questions today in international law and organisation are whether reaffirmation of the concept of collective security and a workable consensus on the means of its realisation are possible. In addressing these questions, this book considers the three key documents in the recent UN reform process: the High-Level Panel report, the Secretary-General's In Larger Freedom report and the 2005 World Summit Outcome document. The chapters examine the responsibilities, commitments, strategies and institutions necessary for collective security to function both in practice and as a normative ideal in international law and relations between state and non-state actors alike.