Enforce the border with bullets. They will stop coming.
There are some mostly unspoken rules about enforcing the border that a lot of Agents understand. That is if we treat those who cross a certain way then the scouts, guides and others involved in trafficking will treat us a certain way.
Of course it is not 100% sometimes Agents are assaulted or killed, but for the most part they won’t do us harm if we don’t harm those who cross.
I knew a former Agent who liked to ride the line of what was allowed as far as use of force went. One day a scout called a supervisor over to the fence and told him because this guy keeps hurting people that they were going to send some fighters across and maybe throw rocks at Agents. The supervisor told him that this guy had been told to stop and would not listen, so the scout said they would only throw rocks at the one Agent and leave the rest alone.
Bottom line is that if people who cross were to be shot at then Agents would also get shot at and to be honest Agents sitting on the line would be easy targets.