The North Atlantic Treaty Organization – or NATO, as it is called – is an intergovernmental military alliance between countries in North America and Europe. The organization oversees the implementation of the North Atlantic Treaty that was originally signed in 1949.
Members of NATO have agreed to a system of collective defense for its members. This simply means that member states will step in and offer mutual defense when one of the member states is attacked by an outside party.
When the organization first began, there were 12 original countries. This number has since grown to 29 as of July 2018. These countries (in alphabetical order) are: Albania, Belgium, Bulgaria, Canada, Croatia, Czech Republic, Denmark, Estonia, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, Montenegro, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Turkey, United Kingdom and United States.
The original 12 founding members were: Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, Netherlands, Norway, Portugal, United Kingdom and United States. Other countries joined throughout the years, with the most recent member being Montenegro, which joined the organization in 2017.
NATO also has what it calls aspiring members, who one day may join other states within NATO. This includes Bosnia and Herzegovina, Georgia, Macedonia and Ukraine. There are also 21 countries that are members of NATO’s Partnership for Peace program. This program is designed to build trust between the organization and states in Europe and the former Soviet Union. Members of this program include former republics of the Soviet Union: Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine and Uzbekistan. Members of the program that are former republics of Yugoslavia are Bosnia and Herzegovina, the Republic of Macedonia and Serbia. European Union members of the program include Austria, Finland, Ireland, Malta and Sweden. Finally, the European Free Trade Association member Switzerland is also part of the Partnership for Peace program.