The Three Seas Initiative has evolved into a geopolitical and geo-economic grouping of primarily post-communist EU member states. Despite their diversity and differences in policies towards Russia, the members are showing certain common interests.

The Three Seas Initiative was originally developed as a geopolitical alliance of NATO/EU member states of “New Europe”: from Estonia to Croatia, connecting the Baltic and Adriatic Seas. The initiative was officially launched in 2015 as the Adriatic-Baltic Sea Initiative by Croatian President Kolinda Grabar-Kitarović and has been referred to as the ABC (Adriatic, Baltic, and Black Sea) Initiative, first designated by Polish President Andrzej Duda. It has also been referred to as “the vertical”, considering the north-to-south direction of the bloc of countries which make up the initiative.