From the 1960s, international terrorist crimes, such as the hijacking of passenger aircraft, political assassinations and kidnappings, and urban bombings, constituted a growing phenomenon of increasing concern, especially to Western governments. Most terrorist groups are associated either with millenarian revolutionary movements on an international scale (such as some Marxist organizations) or with nationalist movements of particular ethnic, religious, or other cultural focus. Three broad categories of terrorist crime may be distinguished, not in legal terms, but by intention. Foremost is the use of violence and the threat of violence to create public fear. This may be done by making random attacks to injure or kill anyone who happens to be in the vicinity when an attack takes place. Because such crimes deny by virtue of their being directed at innocent bystanders, the unique worth of individual, terrorism is said to be a form. of crime that runs counter to all morality and so undermines the foundations of civilization. Another tactic generating fear is the abduction and assassination of heads of state and members of governments in order to make others afraid of taking positions of leadership and so to spread a sense of insecurity. Persons in responsible positions may be abducted or assassinated on the grounds that they are 'representatives' of some institution or system to which their assailants are opposed. A second category of terrorist crime is actual rule by terror. It is common practice for leaders of terrorist organizations to enforce obedience and discipline by terrorizing their own members. A community whose collective interests the terrorist organization claims to serve may be terrorized so that their cooperation, loyalty, and support are ensured. Groups that come to power by this means usually continue to rule by terror. Third, crimes are committed by terrorist organizations in order to gain the means for their own support. Bank robbery, kidnapping for ransom, extortion, gambling rake-offs (profit skimming), illegal arms dealing, and drug trafficking are among the principal crimes of this nature. In the Middle East, hostages are frequently sold as capital assets by one terrorist group to another. Terrorist organizations tend to be associated with any of the following things except ______.