Information technology (IT) is essential to virtually all of the nation s critical infrastructures making them vulnerable by a terrorist attack on their IT system. An attack could be on the system itself or use the IT system to launch or exacerbate another type of attack. IT can also be used as a counterterrorism tool. The report concludes that the most devastating consequences of a terrorist attack would occur if it were on or used IT as part of a broader attack. The report presents two recommendations on what can be done in the short term to protect the nation s communications and information systems and several recommendations about what can be done over the longer term. The report also notes the importance of considering how an IT system will be deployed to maximize protection against and usefulness in responding to attacks.