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.
Accession of Bosnia and Herzegovina to NATO
Despite that all immovable property is not fully registered, NATO approved the activation of the Membership Action Plan for Bosnia and Herzegovina, and called on Bosnia to submit an Annual National Program on 5 December 2018. On 17 December, United States Deputy Secretary of State John Sullivan stated the United States supports Bosnia and Herzegovina's bid to join NATO, and dismissed Serb objections by adding that "Washington would react strongly to any threat to the stability of the country."