The Year 2000 ‘Millenium Bug’ raised awareness amongst governments of the increasing dependency that key elements of the national infrastructure have on computer systems. The dependency on networked computers has now reached a point where a failure of key computer systems could lead to significant impact on national life, government and the economy. National security analysts have been concerned over the possibility that critical computer systems could be a target for strategic attack. The national infrastructure consists of a range key services that are essential for supporting everyday activities within a nation, including energy provision, transportation, telecommunications, finance, water distribution and food production. In addition there are a range of others, such as law and order and financial services, that are part of both national and local infrastructures. The book defines national strategies for improving resilience of computer systems and networks against attack on critical elements of the infrastructure. Strategic options include key actions that government and private owners can take, ranging from deterrence, protection, reaction and recovery. The actions cover a wide spectrum, from political and legal, through to ensuring that the necessary investment in security technologies is made to reduce vulnerability. The strategic concepts are ‘modular’, so that if appropriate components were adopted, there would be a tangible reduction in vulnerability. The book concludes by examining how the programmes of two nations, the US and the UK, compare with the strategic concepts presented, providing practical examples of the steps that can be taken to ensure that national life is protected against cyber attack. The examination is then widened to nations beyond the US and UK that have similar concerns and are taking active steps to put national frameworks for protection in place. Finally the potential for increased international collaboration to strengthen protection and outlaw cyber attack is considered.