This game captures the feel of the Cold War, but it seems it could just as easily be designed to represent the war on terror and the ideological struggles going on now. As nations seek to control dwindling energy reserves and sources around the world, as other resources such as water and food become more and more important, and as warfare turns asymmetrical and fought between shadowy, clandistine intelligence organizations, economic interests, and ideological groups, some of the same paranoia and spy vs spy feel of the Cold War is being replicated again. I think this game could be the basis for an expansion, or even a new edition, based on current events.
Expansions? Ah... no. This game has it all and doesn't need anything else. Sure, they could have gone with a diferent theme, but they chose this one and it works.
I do not endorse an expansion, too. More cards would not make the game better and the game mechanic should not be changed / amplified.