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 NATO
In 2009, US President Barack Obama proposed using the ship-based Aegis Combat System, though this plan still includes stations being built in Turkey, Spain, Portugal, Romania, and Poland. NATO will also maintain the "status quo" in its nuclear deterrent in Europe by upgrading the targeting capabilities of the "tactical" B61 nuclear bombs stationed there and deploying them on the stealthier Lockheed Martin F-35 Lightning II. Following the 2014 annexation of Crimea by Russia, NATO committed to forming a new "spearhead" force of 5,000 troops at bases in Estonia, Lithuania, Latvia, Poland, Romania, and Bulgaria.
The Russian intervention in Crimea in 2014 lead to strong condemnation by NATO nations, and Poland invoked Article 4 meetings. At the subsequent 2014 Wales summit, the leaders of NATO's member states formally committed for the first time spend the equivalent of at least 2% of their gross domestic products on defence by 2024, which had previously been only an informal guideline. In 2015, five of its 28 members met that goal. At the beginning of 2018, eight of the 29 members either were meeting the target or were close to it; six others had laid out plans to reach the target by 2024 as promised; and Norway and Denmark had unveiled plans to substantially boost defense spending (including Norway's planned purchase 52 new F-35 fighter jets.