In central Europe two million combat troops have faced each other for 23 years, mutually suspicious, ready for war. They are the forces of the rival military alliances of NATO and the Warsaw Pact, and they represent the highest concentration of armed force anywhere in the world.

Scared at the prospect of nuclear war, the two sides are attempting to reduce their forces. But reduction must be mutual and balanced. As a background to the current political talks. Horizon examines the doctrines and military strategies of the two alliances and shows how difficult it will be for the two sides to reach agreement. But if they don't, what then?