The North Atlantic Treaty, signed in Washington on April 4, 1949, created an alliance of 10 European and two North American nations committed to each other's defense. Four more European nations joined between 1952 and 1982. The admission of Czech Republic, Hungary and Poland on March 12, 1999, brought the number of members to 19. In 2002, seven new nations were invited to join the alliance.
<<< Click the nations on the map for more information on each member.
Sources: CBS News, The Associated Press, CIA World Fact Book 2002
