Columbia subject headings:
European Union.
North Atlantic Treaty Organization.
Organization for Security and Co-operation in Europe.
Security, International.
Harvard subject headings:
European Union
International relations--Risk assessment
North Atlantic Treaty Organization
Organization for Security and Co-operation in Europe.
Security, International.
Terrorism.
War on Terrorism, 2001-
Princeton subject headings:
European Union.
North Atlantic Treaty Organization.
Organization for Security and Co-operation in Europe.
Security, International--21st century.
Terrorism.