Columbia subject headings:
Europe--Foreign relations--United States.
Europe--Politics and government--1989-
European Union.
National security--Europe.
Harvard subject headings:
Europe--Foreign relations--United States.
European Union
European Union countries--Politics and government.
United States--Foreign relations--Europe.
Princeton subject headings:
Europe--Foreign relations--United States.
Europe--Politics and government--21st century.
European federation--History.
United States--Foreign relations--Europe.