Trump should have closed the border (at least temporarily) on Mexico when he first suggested doing it to let our so-called “southern neighbors” know we’re not taking their BS. In my opinion, he missed a golden opportunity to put Mexico on its heels and make them respect our sovereignty.
The ONLY thing that is respected in this world is strength. Everything else (talk, negotiations, diplomatic niceties, etc.) is rightly perceived as weakness.
I still don’t know why Trump backed away from that. It’s not like the illegal horde (supported by Mexico) has slowed down much.