A plan by the United States for a national missile defence shield to counter any possible nuclear attack has raised a diplomatic furor around the world. China, Russia and a number of other European nations have strongly protested the project. While many U.S. citizens and government officials believe that such a defence system will act as a deterrent, others in the country, as well as in Canada and around the world, present the decades-old argument that such a system will instead lead to the escalation of the development of nuclear weapons throughout the world. As the unofficial diplomatic mediator between the two principal sides in this debate, Canada has been thrust into an important and delicate position. As well as examining the issues, this story also explores how such a proposed system would operate.