[Poohbah]

Why does this need to be a civilian effort given these facts?

"Invasion" has a specific meaning in law, particularly with respect to international borders.

Unless you are saying that this is an actual invasion being conducted by the Mexican government, it's a civil law enforcement issue, and the Posse Comitatus Act forbids the use of the military for civil law enforcement.

[Roscoe]

"Invasion" has a specific meaning in law

Cite and quote.

[Richard-SIA]

Actually, V. Fox is facilitating the invaders passage over our borders.

The Mex. Gov. Org. provides maps, blankets, food and water.

So it could indeed be termed an actual invasion!