Terror attacks on innocent people have continued around the world since 11 September 2001, but not on the scale of the 2001 attack on the United States, which claimed more than 2500 lives. That disaster made us realize our vulnerabilities in many sectors. When a critical industry, such as transportation, communications, energy, or water services, is disrupted in a disaster, it may also cause collateral damage to other services. For example, the 2003 Northeast blackout cut off power to 55 million people. This not only cut off electricity to homes and offices—trains stopped, water purification failed, cell phones went uncharged, and factories shut down. Clearly, attention needs to be paid to improving the resilience of the most critical infrastructure industries.
Branscomb, Lewis M. "Still Vulnerable in 2011." Science, 333.6048, September 9, 2011, 1359.