In the past they were not allowed to stop anyone, sometimes an alien will surrender to them but all they can do is call a border agent. I dont know what they will be allowed to do this time round, maybe they will be allowed to stop someone.
One thing to remember is that in the past they have not had ammunition so stopping someone was a safety concern since they may encounter someone who was armed.
“In the past they were not allowed to stop anyone”
And that is where our leadership failed.