[The Good Doctor]

Seismic tunnel digging detection.

www.elpam.com/products/tunnels-disclosure

Detect and destroy them before they even get close to the barrier.

And obviously the barrier needs to have a component of electrified razor wire. And sensors. And guard towers. And constant human and drone patrols.

Post multi lingual signs for "Danger - High Voltage!"

[PLMerite]

“Post multi lingual signs for “Danger - High Voltage!” “

Or don’t, and just leave the bodies there as a warning.

[Gandalf_The_Gray]

For the benefit of the "greens" we should sequester all the CO2 released by the US in any tunnels we detect.

Regards,
GtG