Terrorism is the use of force or violence against persons or property in violation of the criminal laws of the United States for purposes of intimidation, coercion or ransom. Terrorists often use threats to create fear among the public, to try to convince citizens that their government is powerless to prevent terrorism, and to get immediate publicity for their causes. The Federal Bureau of Investigation (FBI) categorizes terrorism in the United States as one of two types -domestic terrorism or international Terrorism. Domestic terrorism involves groups or individuals whose terrorist activities are directed at elements of our government or population without foreign direction. International terrorism involves groups or individuals whose terrorist activities are foreign-based and/or directed by countries or groups outside the United Stat~s or whose activities transcend national Boundaries. Most terrorist incidents in the United States have been bombing attacks, involving detonated and undetonated explosive devices, tear gas and pipe and fire bombs. The effects of terrorism can vary significantly from loss of life and injuries to property damage and disruptions in services such as electricity, water supply, public transportation and communications. One way governments attempt to reduce our vulnerability to terrorist incidents is by increasing security at airports and other public facilities. The U.S. government also works with other countries to limit the sources of support for terrorism. From 1983 to 1991, the Federal Bureau of Investigation identified 101 terrorist incidents in the United States.