.
NATO
Russia has regained much of its ability to project power abroad, but twelve nations in East Europe are designing a deterrence known as 
Three Seas (launched in 2015 by Croatian and Polish policymakers).
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The 
Three Seas Initiative (3SI, TSI, I3M), also known as the 
Baltic, Adriatic, Black Sea (BABS) Initiative, or simply the 
Three Seas, is a forum of twelve states in the 
European Union, located in 
Central and Eastern Europe. The combined area connects the 
Adriatic Sea, Baltic Sea, and Black Sea. The initiative aims to create a regional dialogue on a variety of questions affecting the member states. The twelve members met for their first summit in 2016, in 
Dubrovnik.
The Three Seas Initiative has twelve member states along a north–south axis from the 
Baltic Sea to the 
Adriatic Sea and the 
Black Sea: 
Austria#, 
Bulgaria*, 
Croatia*, 
Czech Republic*, 
Estonia*, 
Hungary*, 
Latvia*, 
Lithuania*, 
Poland*, 
Romania*, 
Slovakia* and 
Slovenia*. [* = NATO member; # = NATO partner]
The initiative held its first summit in 
Dubrovnik on 25–26 August 2016. The two-day event ended with a 
declaration of co-operation in economic matters, particularly in the field of energy as well as transport and communications infrastructure.
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Intermarium (Polish: Międzymorze; Ukrainian: Міжмор'я, Belarusian: Міжмор’е) was a geopolitical project conceived by politicians in successor states of the former 
Polish–Lithuanian Commonwealth in several iterations, some of which anticipated the inclusion as well of other, neighboring states. The proposed multinational 
polity would have extended across territories lying between the 
Baltic, 
Black and 
Adriatic Seas, hence the 
Latinate name Intermarium, meaning "Between-Seas".
Prospectively a 
federation of 
Central and 
Eastern European countries, the post-
World War I Intermarium plan pursued by 
Polish leader and former 
political prisoner of the 
Russian Empire, 
Józef Piłsudski (1867–1935), sought to recruit to the proposed federation the 
Baltic states (
Lithuania, 
Latvia, 
Estonia), 
Finland, 
Belarus, 
Ukraine, 
Hungary, 
Romania, 
Yugoslavia and 
Czechoslovakia. The Polish name Międzymorze (from między, "between"; and morze, "sea"), meaning "Between-Seas", was rendered into 
Latin as "Intermarium."
The proposed federation was meant to emulate the 
Polish–Lithuanian Commonwealth, stretching from the 
Baltic Sea to the 
Black Sea, that, from the end of the 16th century to the end of the 18th, had united the 
Kingdom of Poland and the 
Grand Duchy of Lithuania. Intermarium complemented Piłsudski's other 
geopolitical vision—
Prometheism, whose goal was the dismemberment of the 
Russian Empire and that Empire's divestment of its territorial acquisitions.
Intermarium was, however, perceived by some Lithuanians as a threat to their newly established independence, and by some Ukrainians as a threat to their aspirations for independence, and while France backed the proposal, it was opposed by 
Russia and by most other Western powers. Within two decades of the failure of Piłsudski's grand scheme, all the countries that he had viewed as candidates for membership in the Intermarium federation had fallen to the 
Soviet Union or 
Nazi Germany, except for Finland (which suffered some territorial losses in the 1939–40 
Winter War with the Soviet Union).