Prevention Terrorism 50 History 33 Foreign relations 19 Politics and government 17 Government policy 16 Military policy 16 more ... War on Terrorism, 2001-2009 13 National security 12 World politics 10 Social conditions 9 History, Military 8 Religious aspects 8 Islam 6 Political aspects 6 Terrorists 5 International cooperation 4 Jihad 4 Security, International 4 Social aspects 4 Weapons of mass destruction 4 Biological warfare 3 Crimes against 3 Hijacking of ships 3 Islamic fundamentalism 3 National characteristics, American 3 Nationalism 3 Nuclear nonproliferation 3 Piracy 3 Psychology 3 less ...