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.
Croatia–NATO relations
Croatia has been a member of the International Security Assistance Force in Afghanistan since December 12, 2002. In 2003 Croatia joined the Adriatic Charter along with other NATO aspirants. In November, 2006 the "State Committee for the Membership of Croatia in NATO" was established, with Croatian president Stjepan Mesić serving as committee president, and speaker Vladimir Šeks and prime minister Ivo Sanader serving as its vice-presidents. In June, 2007 the Croatian Parliament and the NATO parliamentary Assembly held a three-day conference in Dubrovnik entitled "Southeast Europe: Unfinished business", to discuss security and political issues in the region. The Noble Midas 07 NATO exercise held in Croatia in October, 2007 was the first time in the alliance's history that it held a military exercise in a non-member country. Croatia hosted an unofficial meeting of defense ministers on NATO's role in southeastern Europe in March, 2009.