Columbia subject headings:
European Union.
Military history--21st century.
World politics--21st century.
Harvard subject headings:
European Union
European Union countries--Defenses.
European Union countries--Foreign relations.
European Union countries--Military policy.
European cooperation.
Military history--21st century.
World politics
World politics--21st century
Princeton subject headings:
European Union.
Military history--21st century.
World politics--21st century.