I believe the two governments are the ones who are responsible.
We have a corrupt, third world government on our southern border and they all are in effect dumping their problems on us.
Our government should respond to this provocation in a direct manner, country to country. (think what would Putin do?)
Send someone with some credibility (I know, I know), to talk to the Mexican government and tell them to fix their problem or we will have to fix it for them.
Tell Mexico if they can’t control their country we will have to make them a “Protectorate” for the safety of our own country.