Columbia subject headings:
Europe, Central--Foreign relations.
Europe, Eastern--Foreign relations.
National security--Europe, Central.
National security--Europe, Eastern.
Ukraine Conflict, 2014-
Ukraine--Foreign relations--1991-
Ukraine--Politics and government--21st century.
Harvard subject headings:
Europe, Eastern--Foreign relations.
Ukraine Conflict, 2014-
Ukraine--Foreign relations--1991-
Ukraine--Politics and government--21st century.
Princeton subject headings: