NATO Expansion refers to the process of the North Atlantic Treaty Organization (NATO) increasing its membership since the end of the Cold War. Originally formed in 1949 to provide collective defense against the Soviet Union, NATO has welcomed several countries from Eastern Europe, including Poland, Hungary, and the Czech Republic, aiming to enhance security and stability in the region. This expansion has been a subject of debate, with supporters arguing it promotes democracy and security, while critics, including Russia, view it as a threat to their influence and security. The ongoing discussions about further expansion continue to shape international relations in Europe.