Defenses National security -- 6 Civil defense -- 3 Foreign relations -- 3 Military policy 3 Military relations -- 3 Terrorism -- 3 more ... Emergency management -- 2 Politics and government -- 2 Prevention -- 2 Weapons of mass destruction 2 Asymmetric warfare -- 1 Civil defense 1 Conflict management -- 1 Disaster relief -- 1 Economic conditions - 1989- 1 Foreign relations 1 Government policy -- 1 Harbors -- 1 Merchant marine -- 1 Military assistance, American -- 1 National Security 1 National security 1 Nuclear terrorism 1 Nuclear weapons -- 1 Prevention 1 Relations -- 1 Security measures 1 Security measures -- 1 Security, International 1 less ...