At 08:46 on the morning of 11 September 2001, terrorist hijackers flew a passenger plane (flight AA11) into the north tower of the World Trade Center in Manhattan, New York, killing hundreds on impact. Approximately 17 minutes later, at 09:02, another hijacked plane (flight UA175) exploded into the south tower, watched by horrified local onlookers and broadcast on live television around the world. Both skyscrapers (104 floors) collapsed shortly thereafter. Terrorists also flew a third plane (flight AA77) into the Pentagon (the headquarters of the US military) in Arlington, Virginia at 09:37. Another aircraft, flight UA93, which investigators later determined was destined for the White House or the US Capitol Building, was brought down by the passengers on board, crashing into a field in Pennsylvania at 10:03. Intelligence agencies quickly determined that the 19 terrorist hijackers (15 of them were from Saudi Arabia, two from United Arab Emirates and the others from Egypt and Lebanon) were members of the international militant Islamist group al- Qaeda, led by Osama bin Laden. Known simply as “9/ 11”, these tragic events killed nearly 3,000 people (citizens of 78 countries), injured over 6,000 more and caused major economic destruction (the immediate damage was estimated at over $10 billion). It was the largest terrorist incident in history and the deadliest attack on American soil since Pearl Harbor (in which fewer people were killed: 2,400). According to the cover of The Economist (2001 ), it was “the day the world changed”.

In response, the US declared war. Initially, this would involve operations against transnational militant Islamist armed groups, mainly al- Qaeda, as well as the governments that gave them sanctuary – most prominently the Taliban regime in Afghanistan. The US went on to target affiliated jihadist organizations waging insurgencies in various countries, such as Abu Sayyaf in the Philippines, Islamic Jihad in Egypt and the Islamic Movement in Uzbekistan, among many others. As the conflict broadened, the US insisted it would combat terrorism on a worldwide scale, wherever it appeared. From Southeast Asia to the Andean region of South America, numerous localized insurgen-cies and campaigns were subsumed to this singular, overarching war, which profoundly impacted not only US foreign (and domestic) policy but the wider international political agenda.