"There has been a heightened awareness of our vulnerability to cyber attacks in the US and that has been building for over a year. People are saying, 'Look at Lehman Brothers' – if someone had taken out another banking website on the same day it would have been the straw that broke the camel's back," says Tom Reilly, a US director of ArcSight, a company set up by the investment arm of the CIA. It draws 30% of its revenue from monitoring critical infrastructure for dangerous activity for US federal government agencies and Nato.