"On July 21, 1949, the Senate gave its advice and consent to ratification of the North Atlantic Treaty. That treaty bound twelve states -- the United States, Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, and Great Britain -- in a pact of mutual defense and created the North Atlantic Treaty Organization (NATO). NATO now has a membership of twenty-six states. This enlargement has occurred gradually -- Greece and Turkey joined in 1952; the Federal Republic of Germany in 1955; Spain in 1982; Poland, Hungary, and the Czech Republic in 1998; and Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia in 2004. Albania, Croatia, and Macedonia are candidates for the next round of NATO enlargement, and one or more of these countries may be invited to join NATO at the April 2008 summit in Bucharest. […] This report describes the provisions of the North Atlantic Treaty and of the original Senate debate in 1949 pertinent to enlargement and the procedures that have been followed for each subsequent enlargement proposal. It also discusses what the Senate did with respect to the reunification of Germany in 1990 and the implications of that event for Germany's membership in NATO. The report will be updated as needed."
CRS Report for Congress, RL31915