The whole premise of the International Space Station is that it’s meant to be a place where borders, politics, and other issues that drive life on Earth don’t exist. There’s even a pretty big speech to that effect early on in the film. Yet, the second war breaks out, those ideals fall by the wayside. Beyond that, each of the individuals aboard the station shows their true colors when those orders come in. Who is capable of murder? Who is interested in self-preservation? Who is intensely devoted to their country?
Kira and Alexey survived and, perhaps not coincidentally, they both had very little interest in killing or doing the evil bidding of the warmongers back on Earth. When they get in that escape capsule with the radiation sickness research, they both know they are heading towards an uncertain fate. Forget not knowing which country they are going to land in — they don’t even know what Earth is going to look like regardless of where they land. Will there even be much left to save? Will their loved ones be alive? It doesn’t matter. Even if it’s fruitless, they’re doing what they believe is right under truly unfathomable circumstances.
While the ending of “I.S.S.” runs the risk of frustrating the viewer as it leaves on an uncertain note, the question of where Kira and Alexey wind up is sort of inconsequential to the point that is being made. They rise above taking orders from their respective governments. No matter what happens back on Earth, they made a choice for humanity, rather than a choice based on allegiances that are, in all likelihood, all but pointless in the fallout from nuclear war.