[pmulcahy11b]

I'll agree with SGlancy here. When you are a part of a military unit, they become your family in a big way -- that unit becomes your home with an extended family (albeit, often dysfunctional) in it. In the face of World War 3, the survivors of that unit will draw even closer together when they are far away from the US and there's no immediate prospect of going home in sight.

In combat, your fellow soldiers' safety also often becomes more important to you than your own safety. Even in peacetime, letting your fellow soldiers down is really considered low. That too will draw the surviving troops closer together. It may even be what holds together units composed of different nationalities.