Columbia subject headings:
European Union--Defenses.
National security--Europe.
National security--Russia (Federation)
National security--United States.
Russia (Federation)--Defenses.
United States--Defenses.
World politics--21st century.
Harvard subject headings:
European Union--Defenses.
National security--Europe
National security--Russia (Federation)
National security--United States
Russia (Federation)--Defenses.
United States--Defenses.
World politics--21st century
Princeton subject headings:
European Union--Defenses.
National security--Europe.
National security--Russia (Federation)
National security--United States.
Russia (Federation)--Defenses.
United States--Defenses.
World politics--21st century.