Why do they think 9/11 caused such a large shift in the way
agencies communicated?

The module assesses the wider consequences of 9/11 on domestic and world politics, along with the military and political response of the US and the UK to terrorist threats and the changing role of the media (via such methods as embedded reporting), and explores how the British state attempts to balance security and civil liberty in the face of the sudden and shocking arrival of home-grown terrorism on its shores.