Defenses National security -- 6 Civil defense -- 2 Terrorism -- 2 Civil defense 1 Emergency management -- 1 Foreign relations 1 more ... Foreign relations -- 1 Government policy -- 1 Harbors -- 1 Merchant marine -- 1 Military policy 1 National Security 1 National security 1 Nuclear terrorism 1 Nuclear weapons -- 1 Politics and government -- 1 Prevention 1 Prevention -- 1 Relations -- 1 Security measures 1 Security measures -- 1 Strategic aspects 1 War on Terrorism, 2001-2009 1 Weapons of mass destruction 1 World politics -- 1 less ...