International Spacestation gone berserk!

By 2018 the International space station remains 20% uncompleted. When the Nazis appear from behind the moon, the current crew of the station are having problems of their own. Six astronauts from the U.S., Russia, and France, two from each, have grown to hate each other and have divided the space station into zones with buffer zones between each team's area of control. They fight over everything, including who gets to notify Earth of the coming invasion first. Consequently, none of them does, so the attack comes as a complete surprise.