This is a Cold War song. Before "Ground Zero" referred to the World Trade Center ruins, it meant a potential apocalypse that would be caused by either America or the USSR (also see "Christmas at Ground Zero" by Weird Al Yankovic). "Johnny" in this song means an American soldier, while "Ivan" (which is Russian for John) is a Soviet soldier.
This is a Cold War song. Before "Ground Zero" referred to the World Trade Center ruins, it meant a potential apocalypse that would be caused by either America or the USSR (also see "Christmas at Ground Zero" by Weird Al Yankovic). "Johnny" in this song means an American soldier, while "Ivan" (which is Russian for John) is a Soviet soldier.