Columbia subject headings:
Harvard subject headings:
Geopolitics.
North Atlantic Treaty Organization
Russia (Federation)--Foreign relations--Ukraine.
Security, International--European Union countries
Ukraine Conflict, 2014-
Ukraine--Foreign relations--Russia (Federation)
Princeton subject headings:
Crimea (Ukraine)--History--2014-
European Union countries--Foreign relations.
European Union--Defenses.
Geopolitics.
National security--Ukraine--21st century.
Russia (Federation)--Foreign relations--Ukraine.
Security, International--European Union countries.
Ukraine Conflict, 2014-
Ukraine--Foreign relations--Russia (Federation).