Three states that emerged from the old Yugoslav Federation (Croatia, Montenegro, and Slovenia) have joined NATO, while only two (Croatia and Slovenia) have entered the EU. In a sense, these new alliance partnerships have replaced the void left in the absence of the Yugoslav political entity. Alliance politics theory that emphasizes the driving importance of erasing geographic and systemic open spaces is important in this analysis. Separately, Albania has joined NATO while Bulgaria has joined both alliances, and both countries contributed in important ways to alliance global peacekeeping missions. Bulgaria also figured largely in the Western plans to build a defense barrier in light of the Afghan and Iraq wars, but its relationship to Russia has also been a consistent matter of concern and debate.