Enlargement of NATO
As of 2018, NATO officially recognizes four aspiring members: Bosnia and Herzegovina, Georgia, Macedonia and Ukraine. The Federation of Bosnia and Herzegovina within Bosnia and Herzegovina has expressed willingness to join NATO, however, it faces consistent political pressure from Republika Srpska, the other political entity in the country, alongside its partners in Moscow. Macedonia has been prevented from joining the alliance by Greece, one effect of the Macedonian naming dispute. Future expansion is currently a topic of debate in several countries outside the alliance, and countries like Sweden, Finland, and Serbia have open political debate on the topic of membership, while in countries like Ukraine, support and opposition to membership is tied to ethnic and nationalist ideologies. The incorporation of countries formerly part of the Eastern Bloc and the Soviet Union has been a cause of increased tension between NATO countries and Russia.
History of Europe
In 2004, the EU gained 10 new members. (Estonia, Latvia, and Lithuania, which had been part of the Soviet Union; Czech Republic, Hungary, Poland, Slovakia, and Slovenia, five former-communist countries; Malta, and the divided island of Cyprus.) These were followed by Bulgaria and Romania in 2007. Russia's regime had interpreted these expansions as violations against NATO's promise to not expand "one inch to the east" in 1990. Russia engaged in a number of bilateral disputes about gas supplies with Belarus and Ukraine which endangered gas supplies to Europe. Russia also engaged in a minor war with Georgia in 2008.