You gave Denmark as an example, sure they can do it. Denmark's trade with US is very tiny but lets say Russian submarines start showing up near Greenland, what

You gave Denmark as an example, sure they can do it. Denmark's trade with US is very tiny but lets say Russian submarines start showing up near Greenland, what is Denmark going to do, they will go to NATO where you have US calling the shots. Once Russia starts making some noise, all European countries will need US protection.