Whoa -- We're obviously on different wave-lengths.
Yeah, I'm on the conservative wavelength that knows how the military works, and what it does (to wit, kills people, breaks things, and wins wars). You're on the liberal wavelength that thinks the military's a bottomless reservoir of manpower to support your pet project. (It isn't.)
If you put a large fraction of the US military on the border (and closing 2,000 miles of border will, indeed, require a large fraction of the military) on an unending mission, then any international crisis means either (a) the US does nothing, or (b) illegal immigration ramps right back up to present levels. Our enemies would love for us to face such a difficult decision.