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.
Member states of NATO
The United States has a larger defense expenditure than all other members combined. Criticism of the organization by then newly elected US President Donald Trump caused various reactions from American and European political figures, ranging from ridicule to panic. Pew Research Center's 2016 survey among its member states showed that while most countries viewed NATO positively, most NATO members preferred keeping their military spending the same. The response to whether their country should militarily aid another NATO country if it were to get into a serious military conflict with Russia was also mixed. Only in the US and Canada did more than 50% of the people answer that they should.