Defenses National security -- Civil defense -- 2 Terrorism -- 2 World politics -- 2 Civil defense 1 Emergency management -- 1 more ... Government policy -- 1 Harbors -- 1 Merchant marine -- 1 Military policy 1 Military relations -- 1 National security 1 Nuclear terrorism 1 Nuclear weapons -- 1 Politics and government -- 1 Prevention 1 Prevention -- 1 Security measures 1 Security measures -- 1 Security, International 1 War on Terrorism, 2001-2009 1 Weapons of mass destruction 1 less ...