There really are no countries. Cities, states and countries are all just legal fictions. If you look at photographs of Earth from space, there are no borders or lines dividing us other than oceans and bodies of water.
If there was an exestential enemy threatening all of mankind-Almost all humans would band together to defeat it. Right now, we are our own worst enemy. Mostly because we imagine that we are all somehow different. The truth is we are all very much the same. Our humanity binds us together no matter how much we try to fight against it.