gathering. Public sources of information are also invaluable to the guerrilla, from the flight schedules of targeted airlines, to public announcements of visiting foreign dignitaries, to US Army Field Manuals. Modern computer access via the World Wide Web makes harvesting and collation of such data relatively easy. The use of on the spot reconnaissance is integral to operational planning. Operatives will "case" or analyze a location or potential target in depth- cataloging routes of entry and exit, building structures, the location of phones and communication lines, the presence of security personnel, and a myriad of other factors. Finally, intelligence is concerned with political factors such as the occurrence of an election or the impact of the potential operation on civilian and enemy morale. Relationships with the civil population Relationships with civil populations are influenced by whether the guerrillas operate among a hostile or friendly population. A friendly population is of immense importance to guerrillas, providing shelter, supplies, financing, intelligence, and recruits. The "base of the people" is thus the key lifeline of the guerrilla movement. In the early stages of the Vietnam War, American officials "discovered that several thousand supposedly government-controlled 'fortified hamlets' were in fact controlled by Viet Cong guerrillas, who 'often used them for supply and rest havens.'" Popular mass support in a confined local area or country, however, is not always strictly necessary. Guerrilla and revolutionary groups can still operate by using the protection of a friendly regime, drawing supplies, weapons, intelligence, local security, and diplomatic cover. The Al Qaeda organization is an example of the latter type, drawing sympathizers and support primarily from the wide-ranging Muslim world, even after American attacks eliminated the umbrella of a friendly Taliban regime in Afghanistan. An apathetic or hostile population makes life difficult for guerrillas, and strenuous attempts are usually made to gain their support. They may involve not only persuasion but also a calculated policy of intimidation. Guerrilla forces may characterize a variety of operations as a liberation struggle, but that may or may not result in sufficient support from affected civilians. Other factors, including ethnic and religious hatreds, can make a simple national liberation claim untenable. Whatever the exact mix of persuasion or coercion used by guerrillas, relationships with civil populations are one of the most important factors in their success or failure. Use of terror Terror is used to focus international attention on the guerrilla cause, liquidate