I would not mock any US president seriously consideirng to invade and annex Mexico. Its not on the other side of the planet - its right on your doorstep.
However, you then end up in a seat comparable to the Israelis regarding the Palestinians.
Doomed if you do and doomed if you dont.
Walls sometimes are a reasonable solution. Especially when they are not meant to keep own people in (Eastgerman wall), but to keep bad guys out - man has done like that since many, many, many centuries and millenia with his towns and villages.
Its insane what a hopelessly perverted sense of "libelaism" today makes people i the West to agree to. Open boarders. Asylum for everybody. Endless payments to and endless patience for offenders. A whole industry building up around keeping these deformations of a free society alive.
Much of what the idea of free private cities is basing on, is missing in Western states today. And thats why they fail.
https://freeprivatecities.com/
To me, after 200 years of modern democracy and Western statehood, this concept by which the West wants to define itself, has failed. Law and order is in decline, often actively violated by the states themselves. The social systems cannot be maintained anymore. The military potence to defend oneself is being given up. No controls and no border protection there should be. People nmever havign done anything for their new country the ymoved to, imem dioately hslal have all benefits and rights, while all too often not compensating by giving back accordingly.
This cannot go well endlessly. It must crash down, by all rules of logic.