What specifically are the wartime rules of engagement to police the mexican border? That's 1000s of miles - specifically how can that be made impenetrable without resorting to draconian tactics?
"Wartime ROE" is what every sane nation AT WAR employs. You announce loudly and clearly that from now on, "runners" will be stopped, one way or the other. The current Keystone Kops system says, "speed fast on the highway, and we'll drop pursuit" and so on. This encourages the coyotes to take wild risks on the highways, driving backwards against traffic at 100MPH on the shoulder is one such trick. They know the BPs rules are to let them go. This actually leads to MORE deaths.
A firm set of rules will cause coyotes to quit, since their chances of success will drop to near zero. Fewer will die of thirst in the desert, becuase almost nobody will TRY to cross the desert, when they know the risk of aprehension is 99%.
This is what SANE countries do in WARTIME, when terrorists are known to be trying to sneak into your country.
The U.S.-Mexico land border is about 1500 miles long. The total perimeter of the contiguous 48 U.S. is about 18,500 miles.
But, you know, Draconian tactics are just fine as far as the Riders Of The Illegal Immigration Hobbyhorse are concerned. They have no problem with demanding that a person be machine-gunned for trying to find good-paying work, albeit in an illegal manner.