Potential challenges to continental defence remain, however, especially if one looks beyond the near future. Nuclear weapons continue to occupy a central role in Russian military doctrine. China also maintains strategic nuclear forces able to reach North America, and is continuing to modernize its intercontinental systems. The proliferation of weapons of mass destruction and their means of delivery is another concern. A number of states have acquired, or are seeking to acquire, nuclear, chemical and biological weapons, as well as ballistic missile delivery capabilities.
Intercontinental threats constitute a longer-term problem.
None of the nations with the potential to develop this capability is expected to possess ballistic missiles able to reach NorthAmerica until well into the next century. Yet nuclear, chemical, biological and theatre missile programs cannot be discounted in planning for future contingencies. One reason is that sophisticated delivery mechanisms are not required in the case of chemical and biological weapons. In addition, weapons of mass destruction already or may soon threaten Canada's friends and allies in Europe and elsewhere, and Canada may want to retain the option of deploying forces to areas where they could face such weaponry. The institutional basis of Canada-US defence cooperation provides highly valued stability in a volatile and turbulent world.