It's easy to explain why they're here. They know that no one will give the order to run them off.

There was a time not long ago that NO man-o-war from anywhere would have dared to come within 200 miles of our coast without invitation...they would have known that they were being watched and that they wouldn't want to do anything that might be construed as an hostile act.

This is the inevitable unintended consequence of an open borders policy. If people have the right to travel wherever they want, then militaries will presume they have the same right.