In September 2001 the attacks by Al-Qaeda terrorists on the World Trade Centre in New York and the Pentagon in Washington shook world politics deeply. They signalled an end to the uncertainty of the “post-Cold War” era. By generating within the United States an unexpected and profound sense of vulnerability and a determination to prevent such attacks in future, they led the world's only remaining superpower to adopt a much more assertive unilateralism in its policy approaches. Military action followed in Afghanistan and, outside a United Nations framework, in Iraq. In parallel, US policymakers showed a new determination to resist any multilateral constraints on their capacity to act in a number of social as well as political and military areas. These events all struck a dramatic opening chord for early 21st century international relations. In our view, however, another, deeper, more reverberating, note was sounding underneath and through this chord. This was the impact in all its various manifestations of globalisation.

The form, origin and destination of globalisation are all contested. Despite disagreement on its form, origins and destination, a majority opinion within the vast and burgeoning literature on the subject suggests that globalisation is a process, or series of processes, that manifested itself most vigorously in the years after 1990, and is advancing, gaining in momentum, broadening in scope. As the terrorist attacks showed, a globalising world is by no means homogeneous, and it is not necessarily more secure.