In the alternative timeline, where the Cold War ended with the triumph of the Nationalists. One last battle has be fought. Europe is running out of any possible energy resources, the industry is stagnating and European Union's greatest foe - the union of Eastern European rogue states known as the "Intermarum" has issued an economic blockade on its mighty western neighbor. Too long we have tolerated these hordes making illegal genetic experiments on people and polluting our holy continent with the wastes of their nuclear production. Too long they have polluted the North Pole and refused to disarm. It's time, commander. It's time, commander, to break through their failed regime with our legions of steel and fire.
Originally, the idea of creating a united state with such name and territory dates back to 1918 when Józef Piłsudski dreamt of united Eastern Europe able to be a match for both Russia and Germany. Who knows? The country with such name could have appeared on the political maps if not the military conflict between the newly-independent Ukraine and Poland, which alienated and exhausted the two major anti-Bolshevik powers of Eastern Europe'18-20.
In Europe'92 the idea was revived again when the newly established EU proved to be hostile to the former socialist nations. The following schism on Western and Easter European unions and the subsequent establishment of a viable and militarily powerful nation with a population of 150 million is seen as a manifest of Slavic and the whole Eastern European identity.
Not many details are available about the ruling elite, but the official propaganda names "Ms. Kovalenko" ("pani Kowalenko") as the supreme ruler of the federation.
Except internationally-recognized territory Intermarum (or "Międzymorze") claims possession of Crimea (joint-administered territory of Russia, EU, Intermarum and Turan) and has political control of North Saamiland protectorate in the north tip of Europe.
The ideology of Intermarum promotes the eventual unification with the rest of Slav nation currently under control of EU (such as Czech Republic and Croatia). Some radical minds even speak about the need of Russia's ascension to Intermarum.