Columbia subject headings:
Europe--Foreign relations--United States.
North Atlantic Treaty Organization--Armed Forces.
North Atlantic Treaty Organization--Membership.
Terrorism--Prevention--International cooperation.
United States--Foreign relations--Europe.
Harvard subject headings:
Europe--Foreign relations--United States.
North Atlantic Treaty Organization--Armed Forces.
North Atlantic Treaty Organization--Membership.
Terrorism--Prevention--International cooperation
United States--Foreign relations--Europe.
Princeton subject headings:
Europe--Foreign relations--United States.
North Atlantic Treaty Organization--Armed Forces.
North Atlantic Treaty Organization--Membership.
Terrorism--Prevention--International cooperation.
United States--Foreign relations--Europe.