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.
Economics of defense
At the Prague Summit 2002, with the 9/11 terror attack not in the distant past and the enlargement of NATO into Eastern Europe (Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia and Slovenia), member states agreed the need to strengthen the alliances ability to deal with a wide range of new threats. After this submit members countries committed to establishing a minimum level of acceptable defense spending of 2% of annual GDP. As of 2016 figures, only five member states (United States of America, Estonia, United Kingdom, Poland and Greece) have reached this figure .