During a fairly long period of “strategic stability” Soviet Union and United States put a different meaning in this term. Only in June 1990 the two states issued a joint statement where the most general form of an agreed definition appeared. It virtually replaced the old principle of equality and equal security which proved to be too amorphous and, therefore, not binding. The article proposes a detailed analysis of how to maintain the strategic stability in the light of new threats and processes which will inevitably lead to its erosion and will increase the likelihood of combat or terrorist use of nuclear weapons, with devastating consequences for all modern civilization.