Southeast Europe
This concept is based on the boundaries of the Balkan peninsula. The countries that have been described as being entirely within the region are: Albania, Kosovo, Bosnia and Herzegovina, Bulgaria, Macedonia and Montenegro.
Nuclear-weapon-free zone
The other European countries west of the former Soviet Union
are small Western European states and surrounded by and aligned with the EU and NATO but not members (Switzerland and European microstates Liechtenstein, Monaco, San Marino, Vatican, Andorra), or Balkan states that have not yet joined the EU (Albania, Bosnia, Montenegro, Macedonia, Serbia and Kosovo).