In the 1970's, terrorists refused to create a public disaster due to their desire to win public opinion to their side. Terrorist groups were mainly leftist, anarchist movements, separatist, and nationalist groups. Both the strategies and the perpetrators changed markedly in the 1980's. During that decade, terrorism was practiced by national intelligence operations and changed in strategy from spreading fear to inflicting heavy destruction to influence decisionmaking. In addition, suicidal tactics have replaced the traditional tactics of hostage-taking and threats. Terrorists have used every scientific innovation developed, so it is likely that they will use nuclear weapons. The growth in the use of nuclear power and the spread of scientific knowledge on how to make a bomb both make it possible for terrorists to manufacture, steal, or buy a bomb, although some experts consider it unlikely that they will. However, the most dangerous factor currently is the existence of rich nations among the developing nations that are eager to break the nuclear monopoly and that have no concern for peace.