Columbia subject headings:
National security--United States.
United States--Foreign relations--20th century.
United States--Foreign relations--21st century.
Harvard subject headings:
National security--United States
United States--Foreign relations--20th century.
United States--Foreign relations--21st century.
Princeton subject headings:
National security--United States.
United States--Foreign relations--20th century.
United States--Foreign relations--21st century.